J123606+620951 (unclassified) is undetected at 8.4GHz and thus has a radio J123606+620951 spectrum with alpha>0.56. It has a compact (<0.2arcsec) J123606+620951 component with weak extended emission. The radio source lies J123606+620951 outside the CFHT image so no optical frame is shown in Fig. C1. J123606+620951 However, Cowie et al. (2004, Cat. ) catalogue J123606+620951 an R=22.7mag galaxy at the position of the radio source with J123606+620951 a redshift of 0.6379. It is detected by Chandra. J123606+621021 (starburst candidate) is separated from J123608+621035 by 17" but J123606+621021 does not appear to be related to it. The radio structure is J123606+621021 extended over 0.7-arcsec. It lies outside the area of the CFHT J123606+621021 image so no optical frame is shown in Fig. C1. However, Chapman J123606+621021 et al. (2004ApJ...611..732C) catalogue an J123606+621021 I=23.8mag submillimetre galaxy (S_850_=11.6+/-3.5mJy) at the J123606+621021 position of the radio source with a redshift of 2.33. J123606+621021 There is a faint Chandra counterpart. J123607+621328 (starburst candidate) is extended over 1.2" roughly north-south. J123607+621328 This source lies outside the CFHT image so no optical frame is J123607+621328 shown in Fig. C1. However, Cowie et al. (2004, J123607+621328 Cat. ) catalogue an R=21.8mag galaxy at the J123607+621328 position of the radio source with a redshift of 0.4353. J123608+621035 (AGN) has a relatively flat radio spectrum overall (alpha=0.36). J123608+621035 It has a compact core and two-sided radio emission. The compact J123608+621035 component lies at the nucleus of a 20.6-mag galaxy with a J123608+621035 redshift of 0.681 (Cowie et al., 2004, Cat. ). J123608+621035 It is detected by Chandra. J123608+621553 (starburst candidate): Richards (2000ApJ...533..611R) states that J123608+621553 this source has an inverted radio spectrum (alpha=0.24). It is J123608+621553 extended by approximately 0.5arcsec. It is identified with an J123608+621553 I=21mag galaxy at the very edge of the CFHT frame with a J123608+621553 redshift of 0.4593 (Cowie et al., 2004, Cat. ). J123608+621553 No compact AGN core is seen, therefore it is most likely that J123608+621553 the radio emission originates in an extended starburst with J123608+621553 strong free-free absorption at 1.4GHz to account for the J123608+621553 spectral shape. It is detected by Chandra. J123608+621431 (starburst candidate) is extended by 1-arcsec east-west and is J123608+621431 identified with a 23.7-mag galaxy of the CFHT frame. J123610+620810 (unclassified) has a relatively compact component with weak J123610+620810 extended emission 0.6-arcsec to the south-west at 0.5-arcsec J123610+620810 resolution (not shown). No optical information is available J123610+620810 since it lies outside the area of the CFHT frame. J123610+621651 (unclassified) has extended radio emission (0.9-arcsec) on both J123610+621651 sides of a relatively compact component at 0.2-arcsec resolution J123610+621651 (not shown), which is coincident with the nuclear region J123610+621651 of a I=23.7mag galaxy. J123612+621138 J123612+621138/J123612+621140 (starburst candidates) are J123612+621138 separated by 4-arcsec. J123612+621140 has a steep radio spectrum J123612+621138 (alpha>0.89). J123612+621138 has no spectral index measurement J123612+621138 although the radio sources are only partially separated by J123612+621138 Richards (2000ApJ...533..611R) who classifies the pair as a J123612+621138 single object. Each one appears to be an extended starburst and J123612+621138 is identified with a separate galaxy in a system which appears J123612+621138 to be interacting. J123612+621138 is identified with J123612+621138 an I=18.9mag galaxy; J123612+621140 is identified with J123612+621138 an I=19.4mag galaxy. Cowie et al. (2004, Cat. ) J123612+621138 measure the same redshift for each galaxy (z=0.275). J123612+621138 J123612+621138 is detected by Chandra. J123612+621140 See J123612+621138 J123615+620946 (starburst candidate) is extended over 0.8-arcsec and overlies J123615+620946 the nuclear region of an I=22.0mag galaxy with a redshift J123615+620946 of 1.263 (Cowie et al., 2004, Cat. ). J123616+621513 (starburst candidate) is extended over 1-arcsec. The weak J123616+621513 extended emission 3-arcsec to the north-west is only visible at J123616+621513 low resolution and has no optical counterpart. It is not thought J123616+621513 to be associated with J123616+621513 and falls below the 7 J123616+621513 detection threshold for the 10-arcmin field sample. J123616+621513 J123616+621513 is identified with an I=22.9mag galaxy. J123616+621513 Chapman et al. (2004ApJ...611..732C) identify the system as J123616+621513 a submillimetre galaxy (S_850_=5.8+/-1.1mJy) with a redshift of J123616+621513 3.61. It is detected by Chandra. J123617+621011 (unclassified) is extended over 0.6-arcsec and contains a J123617+621011 compact component at 0.2-arcsec resolution (not shown). The J123617+621011 nature of the object is unclear since the radio structure could J123617+621011 originate from AGN or starburst activity (or both). It is J123617+621011 identified with an I=21.6mag galaxy. Hornschemeier et al. J123617+621011 (2001, Cat. ) find a single emission line J123617+621011 at 6879.3{AA} which they assign as [O II] at a redshift of J123617+621011 0.845. It is detected by Chandra with a X-ray luminosity J123617+621011 strongly suggestive of AGN activity. J123617+621540 (unclassified) has a fairly steep radio spectrum (alpha>0.55). J123617+621540 It contains a compact component with two-sided emission extended J123617+621540 over 1.3-arcsec. It is identified with a faint galaxy J123617+621540 (I=23.9mag) in a complex region on the CFHT frame. J123618+621635 (AGN candidate) contains two extended radio components separated J123618+621635 by 2.5-arcsec. The radio component to the south-east overlies J123618+621635 the central region of an I=19.7mag galaxy and shows no evidence J123618+621635 for any compact core. The north-western radio component appears J123618+621635 to be associated with a second galaxy which may be part of an J123618+621635 interacting system. Hornschemeier et al. (2001, J123618+621635 Cat. ) find two emission lines from the J123618+621635 south-eastern component which they assign to be [O III] at a J123618+621635 redshift of 0.679. It is also detected by Chandra. On the basis J123618+621635 of the X-ray luminosity and a weak [Ne V] feature, Hornschemeier J123618+621635 et al. (2001, Cat. ) suggest that this object is J123618+621635 an AGN system. J123618+621550 (unclassified) exhibits a steep radio spectrum (alpha>0.63) J123618+621550 compact component with one-sided emission extended over J123618+621550 0.4-arcsec. It is unidentified at the limit of the CFHT frame. J123618+621550 Chapman et al. (2004ApJ...611..732C) identify the system J123618+621550 as a possible submillimetre galaxy (S_850_=7.3+/-1.1mJy) with a J123618+621550 redshift of 1.87. However, this identification is uncertain J123618+621550 since the measured redshift is for the optical object J123618+621550 approximately 0.5-arcsec to the south-west of the radio source; J123618+621550 this is above the nominal astrometric alignment errors for the J123618+621550 position of the radio source in the 10-arcmin field. J123619+621252 (starburst candidate) has a steep radio spectrum (alpha>0.8) and J123619+621252 has radio emission extended over 0.4-arcsec. It lies at the J123619+621252 nucleus of an I=19.9mag galaxy at redshift =0.473 (Cowie et al. J123619+621252 2004, Cat. ). The optical galaxy appears to have J123619+621252 a companion and may be part of a merging system. J123619+621252 It is detected by Chandra. J123620+620844 (AGN) has a flat radio spectrum (alpha=0.01) and shows a compact J123620+620844 core with a one-sided (0.6-arcsec) extension to the east. J123620+620844 The core component overlies the nucleus of an I=21.5mag galaxy J123620+620844 at a redshift of 1.0178 (Cowie et al., 2004, ). J123621+621109 (starburst candidate) has a steep radio spectrum (alpha>0.86). J123621+621109 The VLA-only image (not shown) reveals additional low surface J123621+621109 brightness emission extending over 3-arcsec to the north-east. J123621+621109 A brighter but still extended component is seen in the J123621+621109 combination image and overlies the fainter, south-western member J123621+621109 of an I=21.8mag pair of merging galaxies at a redshift of 1.014 J123621+621109 (Cohen et al., 2000, Cat. ). J123621+621109 There is a Chandra counterpart. J123621+621708 (unclassified) has a steep radio spectrum (alpha>0.56) and J123621+621708 contains a compact component with one-sided emission extending J123621+621708 to the south-east. An extended radio component lies 2.5-arcsec J123621+621708 to the north-west, close to the position of an I=23.4mag galaxy J123621+621708 on the CFHT frame. There is no optical object brighter than J123621+621708 I=25mag at the position of the compact radio component. Chapman J123621+621708 et al. (2004ApJ...611..732C) identify the system as a J123621+621708 possible submillimetre galaxy (S_850_=7.8+/-1.9mJy) with a J123621+621708 redshift of 1.99. However, this identification is uncertain J123621+621708 since the measured redshift is for the galaxy to the north-west J123621+621708 of the radio source; this is well above the nominal astrometric J123621+621708 alignment errors for the position of the radio source in J123621+621708 the 10-arcmin field. J123622+621544 (AGN candidate): has a steep radio spectrum (alpha>0.6). The J123622+621544 radio structure is extended and low surface brightness emission J123622+621544 seen in the VLA-only image (not shown) extends for nearly J123622+621544 3-arcsec to the north-west. A brighter region of emission region J123622+621544 lies 0.75-arcsec to the south-east of the bright nucleus of an J123622+621544 I=19.8mag spiral galaxy in the HFF at a redshift of 0.6471 J123622+621544 (Cowie et al. 2004, Cat. ). As the radio emission J123622+621544 extends well beyond the optical galaxy, the source is classified J123622+621544 as an AGN candidate with an undetected core. There is a J123622+621544 faint Chandra counterpart. J123622+621629 (starburst candidate) is extended (1.3-arcsec) and is identified J123622+621629 with an I=23.8mag galaxy on the CFHT frame. Chapman et al. J123622+621629 (2004ApJ...611..732C) identify the system as a J123622+621629 submillimetre galaxy (S_850_=7.7+/-1.3mJy) with a redshift J123622+621629 of 2.40. There is a faint Chandra counterpart. J123622+620945 (starburst candidate) is extended over ~0.8-arcsec and shows J123622+620945 evidence for double structure at position angle 110{deg}. There J123622+620945 is no evidence of any compact radio structure at full J123622+620945 resolution. The source overlies the nuclear region of an J123622+620945 I=21.1mag galaxy with a redshift of 0.7479 (Cowie et al., J123622+620945 2004, Cat. ). J123623+621642 (AGN candidate) has a steep radio spectrum (alpha=0.63) and J123623+621642 contains a compact component together with one-sided extended J123623+621642 emission. It is identified with an I=23.9mag galaxy in a complex J123623+621642 region on the CFHT frame. J123624+621017 (unclassified) consists of two extended components separated by J123624+621017 2.1-arcsec at position angle 30{deg}. Each component is J123624+621017 ~0.5-arcsec in size and there is no evidence for any compact J123624+621017 radio structure at 0.2-arcsec resolution. The source cannot be J123624+621017 identified with any optical object brighter than I=25mag in J123624+621017 the HFF frame. J123624+621743 (unclassified) shows a compact feature in the 0.2-arcsec image J123624+621743 (not shown) with additional emission extending over 0.9-arcsec. J123624+621743 It is identified with a I=22.9mag galaxy and has a faint J123624+621743 Chandra counterpart. J123629+621045 (unclassified) has a steep radio spectrum with alpha>0.86 and is J123629+621045 extended east-west over 2.7-arcsec with no evidence of compact J123629+621045 emission at the highest angular resolution. The eastern end of J123629+621045 the radio source is coincident with the nucleus of an I=22.2mag J123629+621045 galaxy at a redshift of 1.013 on the CFHT frame (Cohen et al. J123629+621045 2000), but the extension is not correlated J123629+621045 with optical emission. Chapman et al. (2004ApJ...611..732C) J123629+621045 identify this system as a submillimetre source J123629+621045 (S_850_=5.0+/-1.3mJy). It is detected by Chandra. J123630+620923 (starburst candidate) is extended over 0.6-arcsec and overlies J123630+620923 the nuclear region of an I=22.5mag galaxy on the CFHT frame with J123630+620923 an estimated photometric redshift of 0.953 (Bauer et al. J123630+620923 2002AJ....123.1163B). It is detected by Chandra. J123630+620851 (starburst candidate) is extended over 3.3-arcsec. The extension J123630+620851 is more clearly seen in the VLA-only image (not shown) and J123630+620851 additional flux is seen with the Westerbork radio telescope, J123630+620851 indicating possible emission on the 10-arcsec scale. The radio J123630+620851 structure roughly follows the optical isophotes of a complex J123630+620851 galaxy system that appears to be interacting, the brightest J123630+620851 member of which has I=22.6mag. J123631+620957 (unclassified) has a steep radio spectrum (alpha>0.99) and a J123631+620957 compact component with two-sided emission extending over J123631+620957 0.8-arcsec. There is no optical counterpart brighter than J123631+620957 I=25mag on the HFF frame but it has a faint Chandra counterpart. J123632+621658 (starburst candidate) is extended over ~4-arcsec on the VLA-only J123632+621658 image (not shown) and shows no sign of compact emission at J123632+621658 higher resolution. The source is very heavily resolved with J123632+621658 MERLIN and the position in Table A1 is taken from the VLA-only J123632+621658 image at 2-arcsec resolution. The source is associated with an J123632+621658 I=18.2mag spiral galaxy with a redshift of 0.437 (Cowie et al. J123632+621658 2004, Cat. ). J123632+620759 (unclassified) has a steep radio spectrum (alpha>0.58) and is J123632+620759 extended over some 2.6-arcsec on the VLA-only image (not shown). J123632+620759 At higher resolution a compact component is found with J123632+620759 two-sided extended emission, although the majority of the J123632+620759 extended emission seen in the VLA-only image is resolved out. J123632+620759 The radio source lies outside the CFHT frame so no optical image J123632+620759 is shown in Fig. C1. However, Cowie et al. J123632+620759 (2004, Cat. ) catalogue an R=24.0mag galaxy at J123632+620759 the position of the radio source with a redshift of 1.9939. J123632+620759 It is detected by Chandra. J123633+621005 (starburst candidate) has a steep radio spectrum (alpha>0.98) and J123633+621005 is extended over approximately 1.2-arcsec. There is no evidence J123633+621005 for any compact emission at the highest angular resolution. It J123633+621005 overlies a face-on I=21.6mag spiral galaxy at a redshift of J123633+621005 1.016 (Cowie et al., 2004, Cat. ) J123633+621005 on the HFF frame. It is detected by Chandra. J123634+621213 (starburst) has a steep radio spectrum (alpha=0.74). The extended J123634+621213 radio emission is two-sided, surrounding a compact component. J123634+621213 However, EVN observations at 20-mas resolution do not detect J123634+621213 this compact component (Garrett et al. 2001A&A...366L...5G). J123634+621213 The source is identified with a bright disc galaxy (I=18.7mag), J123634+621213 at a redshift of 0.456 (Cowie et al. 2004 Cat. ). J123634+621213 The HFF optical image shows evidence for a dust lane or possible J123634+621213 double nucleus which may indicate a recent merger. The brightest J123634+621213 radio emission lies between the optical nuclei and the J123634+621213 extensions follow the optical isophotal ridge-line. The galaxy J123634+621213 is also detected by ISO with S15um=448uJy. X-ray emission is J123634+621213 detected by Chandra. J123634+621241 (starburst) has a steep radio spectrum (alpha=0.74). There is J123634+621241 extended emission to the south-west of a compact component which J123634+621241 is not detected by the EVN at 20-mas resolution (Garrett et al. J123634+621241 2001A&A...366L...5G). The compact component overlies the nuclear J123634+621241 region of an I=22.3mag Scd galaxy at a redshift of 1.219 on the J123634+621241 HFF WFPC2 frame (Cohen et al., 2000, Cat. ). It J123634+621241 has an mid-infrared flux density S15um=363uJy as detected by J123634+621241 ISO, which implies a substantial star formation rate. This J123634+621241 source is the most likely radio counterpart to SCUBA HDF 850.7 J123634+621241 (see Section 8.4.6). There is a faint Chandra counterpart. J123635+621424 (starburst+AGN?) has a steep radio spectrum (alpha>0.87). It J123635+621424 appears relatively compact, with an angular size of only J123635+621424 0.3-arcsec, in contrast to the earlier angular size estimate of J123635+621424 2.8-arcsec reported by Richards et al. (1998AJ....116.1039R). J123635+621424 The radio source overlies the bright optical nucleus of a J123635+621424 face-on I=22.6mag spiral galaxy on the HFF frame. The spatial J123635+621424 extent of the galaxy suggests that it is of low to moderate J123635+621424 redshift. However, Bauer et al. (2002AJ....123.1163B) list this J123635+621424 object as having a spectroscopic redshift close to 2 and Dawson J123635+621424 et al. (2002, Cat. ) assign a redshift J123635+621424 of 2.011 from several detected emission lines. It is an ISO J123635+621424 detection, and Chapman et al. (2004ApJ...611..732C) identify the J123635+621424 system as a submillimetre galaxy (S_850_=5.5+/-1.4mJy) at a J123635+621424 redshift of 2.01. It is detected by Chandra. Dawson et al. J123635+621424 (2002, Cat. ) argue that the 15-m and X-ray J123635+621424 detections are indicative of an AGN system. If this object is a J123635+621424 compact nuclear starburst system, the implied star formation J123635+621424 rate from the radio and infrared flux densities is J123635+621424 very large (1800M/yr). J123636+621320 (starburst candidate) is extended over approximately 0.7-arcsec J123636+621320 and shows no sign of compact emission. There is no optical J123636+621320 counterpart brighter than I=25mag at the radio source position J123636+621320 on the HFF frame. There is a faint Chandra counterpart. J123637+620852 (starburst candidate) has a steep radio spectrum (alpha>0.82), is J123637+620852 extended east-west over approximately 1.1-arcsec and shows no J123637+620852 sign of a compact component. It is identified with an I=24.5mag J123637+620852 galaxy in a complex region on the CFHT frame. J123640+621009 (AGN candidate) consists of two components separated by J123640+621009 1.2-arcsec. The source as a whole has a radio spectrum of J123640+621009 alpha=0.44, which suggests the presence of a flat-spectrum J123640+621009 component. The 8.4-GHz position (Richards et al. J123640+621009 1998AJ....116.1039R) is close to the northerly component, J123640+621009 indicating that it has a flat spectrum and therefore may be J123640+621009 associated with an AGN. Although no evidence for a compact J123640+621009 feature can be found at 1.4GHz, the radio image has a low J123640+621009 signal-to-noise ratio. The more northerly component overlies a J123640+621009 faint compact I=23.9mag galaxy on the HFF frame. J123641+620948 (unclassified) has a steep radio spectrum (alpha>0.56) and J123641+620948 contains a compact radio component with some extended emission J123641+620948 with a total angular extent of approximately 0.6-arcsec. The J123641+620948 compact component coincides with the nucleus of an I=20.2mag J123641+620948 disc galaxy at a redshift of 0.518 which may be part of a J123641+620948 merging system (Cohen et al., 2000, Cat. ). The J123641+620948 extended radio emission lies perpendicular to the major axis of J123641+620948 the optical galaxy. There is a faint Chandra counterpart. J123642+621331 (starburst+AGN?) has a steep radio spectrum (alpha=0.94). The J123642+621331 radio structure consists of a compact component together with J123642+621331 emission extended over 0.4-arcsec. Garrett et al. J123642+621331 (2001A&A...366L...5G) detect the dominant compact component with J123642+621331 the EVN at an angular resolution of 20mas; it may therefore be J123642+621331 a steep-spectrum AGN core. There is no optical counterpart at J123642+621331 the detection threshold in the HFF I-band image. Waddington et J123642+621331 al. (1999ApJ...526L..77W) detect a very red object at the J123642+621331 radio source position with NICMOS, in J and H band, and with the J123642+621331 KPNO 4-m in K band. On the basis of a single Ly{alpha} emission J123642+621331 line and the observed spectral energy distribution, they ascribe J123642+621331 a redshift of 4.424 and argue that it is a distant starburst J123642+621331 galaxy with a weak embedded AGN. This interpretation is J123642+621331 consistent with the radio morphology. The source is detected by J123642+621331 both ISO and Chandra. J123642+621545 (unclassified) has an intermediate radio spectrum (alpha=0.50). J123642+621545 The radio structure consists of a compact component and extended J123642+621545 emission to the north-east and south-west with the latter J123642+621545 reaching nearly 1.5-arcsec from the core. The core component J123642+621545 overlies the nucleus of an I=20.7mag galaxy on the CFHT frame at J123642+621545 a redshift of 0.857 (Hornschemeier et al., 2001, J123642+621545 Cat. ). The source is detected by both ISO and J123642+621545 Chandra; the compact component could be an AGN, but the nature J123642+621545 of this object remains unclear. J123644+621133 (AGN - FRI radio galaxy) has a bright core with a flat radio J123644+621133 spectrum (alpha=0.1, Richards et al. 1998AJ....116.1039R) with J123644+621133 steep-spectrum emission oriented north-south and extending for J123644+621133 about 15-arcsec in the VLA-only image (not shown). Overall the J123644+621133 radio source exhibits a classical FRI structure. It is optically J123644+621133 identified with an I=20.9mag elliptical galaxy at a redshift of J123644+621133 1.050 (Cohen et al., 2000, Cat. ). This source is J123644+621133 not catalogued by Aussel et al. (1999 Cat. ), but J123644+621133 Goldschmidt et al. (1997MNRAS.289..465G) list a nearby J123644+621133 ISO detection at 6.7um only; Mann et al. (1997MNRAS.289..482M) J123644+621133 identify this with the host of J123644+621133. J123644+621133 There is a faint Chandra counterpart. J123645+620754 (unclassified) lies close to the edge of the 10-arcmin field. The J123645+620754 source is extended east-west over some 3-arcsec, and there is no J123645+620754 evidence for any compact emission. The position given in J123645+620754 Table A1 is from the VLA-only image at 2-arcsec resolution. The J123645+620754 radio source lies outside the CFHT frame so no optical image is J123645+620754 shown in Fig. C1. However, Cowie et al. (2004, J123645+620754 Cat. ) catalogue an R=23.0mag galaxy at the J123645+620754 position of the radio source with a redshift of 1.433. J123645+620754 There is a faint Chandra counterpart. J123646+621448 (unclassified) has a steep radio spectrum, (alpha>0.84) and J123646+621448 contains a compact component with a one-sided 0.5-arcsec J123646+621448 extension at a position angle of 160{deg}. It is not identified J123646+621448 on the HFF frame to approximately I=25mag. However, on the lower J123646+621448 resolution CFHT frame it overlies a faint but distinct galaxy J123646+621448 (I=25.5mag). Chapman et al. (2004ApJ...611..732C) identify this J123646+621448 system as a submillimetre source (S_850_=10.3+/-2.2mJy). J123646+621448 There is a faint Chandra counterpart. J123646+621629 (starburst candidate) has a very steep radio spectrum J123646+621629 (alpha>1.62). The radio structure consists of a compact central J123646+621629 feature together with extended emission distributed J123646+621629 symmetrically around it with a total angular extent of J123646+621629 about 2.4-arcsec. The radio core is coincident with the nuclear J123646+621629 region of an I=19.8mag galaxy at a redshift of 0.502 J123646+621629 (Cohen et al., 2000, Cat. ). J123646+621404 (AGN) has an inverted radio spectrum (alpha=0.04). The radio J123646+621404 structure has a compact component and two-sided extended J123646+621404 emission. The radio emission overlies the nucleus of a nearly J123646+621404 face-on disc galaxy (I=20.7mag) at a redshift of 0.961 (Cowie et J123646+621404 al., 2004, Cat. ), which exhibits a broad J123646+621404 emission line spectrum (Phillips et al. 1997ApJ...489..543P). J123646+621404 These observations combine to form strong evidence that this J123646+621404 galaxy contains an AGN. This radio source was detected by ISO J123646+621404 with S7um=52uJy and it has a bright Chandra counterpart. J123646+621404 Although Rowan-Robinson et al. (1997MNRAS.289..490R) J123646+621404 interpret this source as a massive starburst, star formation J123646+621404 seems unlikely to be powering the bulk of the radio emission J123646+621404 in this object. J123646+620833 (starburst candidate) has a steep radio spectrum (alpha>0.61). J123646+620833 The radio structure is extended over 0.8-arcsec and shows no J123646+620833 sign of compact emission at 0.2-arcsec resolution. The radio J123646+620833 emission overlies the nuclear region of an I=20.6mag galaxy at a J123646+620833 redshift of 0.9712 (Cowie et al., 2004, Cat. ). J123646+620833 There is a faint Chandra counterpart. J123646+621226 (unclassified) has a steep radio spectrum (alpha>1.14) and is J123646+621226 completely resolved out at 0.2-arcsec resolution. The VLA-only J123646+621226 image (as shown in Fig. C2) shows the source to be 3.2-arcsec in J123646+621226 extent. No optical counterpart brighter than I=28mag is found at J123646+621226 the radio position. Deep near-infrared observations (Thompson et J123646+621226 al. 1999) place magnitude limits of I_AB_>28.5, J_110_>29 and J123646+621226 H_160_> 29mag. J123646+621445 (unclassified) has a steep radio spectrum (alpha=0.98) and is J123646+621445 extended over 2.3-arcsec with the major axis roughly aligned J123646+621445 with J123646+621448 which lies 6-arcsec to the north-west. J123646+621445 However, J123646+621445 overlies a fairly compact faint J123646+621445 (I~23.9mag) galaxy. Since both sources overlie separate optical J123646+621445 identifications, it is most likely that they are unrelated. J123646+621445 The I=20.4mag galaxy 2.5-arcsec to the north-east of J123646+621445 J123646+621445 has a measured redshift of 0.558 (Cohen et al., J123646+621445 2000, Cat. ), but does not seem to be related to J123646+621445 the radio source. The ISO source at 4-arcsec separation in a J123646+621445 similar direction cannot therefore be identified with the J123646+621445 radio source with any confidence. J123649+621313 (starburst) has a steep radio spectrum (alpha=0.72) with no J123649+621313 evidence of any compact structure at 0.2-arcsec resolution. It J123649+621313 is extended by approximately 1-arcsec along the major axis of J123649+621313 an I=21.1mag disc galaxy at a redshift of 0.475 (Cohen et al., J123649+621313 2000, Cat. ). The galaxy is in the ISO catalogue J123649+621313 of HDF sources with S15um=320uJy and may be associated with J123649+621313 SCUBA HDF 850.4 (see Section 8.4.3). There is a faint Chandra J123649+621313 counterpart. Low-level radio emission below the formal detection J123649+621313 threshold (and hence not in the catalogue) may also be seen from J123649+621313 an I=22.7mag disc galaxy located about 3-arcsec to the north J123649+621313 which lies at a redshift of 1.238 (Cohen et al., 2000, J123649+621313 Cat. ). J123650+620801 (starburst candidate) is extended by approximately 0.7-arcsec and J123650+620801 shows no sign of compact structure at 0.2-arcsec resolution. The J123650+620801 radio source lies outside the CFHT image so no optical frame is J123650+620801 shown in Fig. C1. However, Cowie et al. (2004, J123650+620801 Cat. ) catalogue an R=22.2mag galaxy at the J123650+620801 position of the radio source with a redshift of 0.559. J123650+620844 (starburst candidate) has a steep spectrum (alpha>0.80). The J123650+620844 radio structure shows a compact component together with extended J123650+620844 emission of approximately 0.8-arcsec extent. The compact J123650+620844 component overlies the nucleus of an I=20.0mag galaxy at a J123650+620844 redshift of 0.434 (Cowie et al., 2004, Cat. ). J123651+621030 (starburst) has a steep spectrum (alpha=0.74). The radio source J123651+621030 is extended over 1.2-arcsec and overlies the nuclear region of an J123651+621030 I=19.9mag disc galaxy at a redshift of 0.410 (Cohen et al., 2000, J123651+621030 Cat. ). It is detected by ISO with S15um=341uJy. J123651+621030 There is a faint Chandra counterpart. J123651+621221 (starburst+AGN?) has a steep spectrum (alpha>0.71). The J123651+621221 MERLIN+VLA image shows a source extended over 1.2-arcsec with J123651+621221 no evidence for any compact component. Garrett et al. J123651+621221 (2001A&A...366L...5G) also find no evidence for any compact J123651+621221 component with the EVN at an angular resolution of 20mas. The J123651+621221 radio structure thus favours a starburst rather than an AGN J123651+621221 interpretation. The radio source is identified with very faint J123651+621221 emission (I>28mag) on the HDF frame. Dickinson et al. J123651+621221 (2000ApJ...531..624D) and Dickinson (2000, Phil. Trans. R. Soc. J123651+621221 London A, 358) report a very red object (IAB= 27.8mag, J123651+621221 J110H160= 1.6) at the position of this source from NICMOS J123651+621221 observations, implying a dust-obscured starburst system at a J123651+621221 redshift approaching 3. The source is detected by ISO with J123651+621221 S15um=48uJy. Hornschemeier et al. (2001, Cat. ) J123651+621221 find a hard X-ray detection with Chandra, suggesting an obscured J123651+621221 QSO at a redshift of 2.7. J123651+621221 The bright (I=21mag) galaxy lying 1.5-arcsec to the south is at J123651+621221 a redshift of 0.401 (Cohen et al., 2000, Cat. ), J123651+621221 and is not thought to be related to the radio source. J123652+621444 (AGN) has an inverted spectrum (alpha=0.12) (Richards et al. J123652+621444 1998AJ....116.1039R) and is observed to vary in intensity on a J123652+621444 time-scale of months, suggesting the presence of an AGN J123652+621444 (Richards 2000ApJ...533..611R). The radio structure shows a J123652+621444 compact core and one-sided jet-like feature to the east J123652+621444 1.3-arcsec in length. The low-resolution WSRT image of this J123652+621444 source (Garrett et al. 2002A&A...384L..19G) shows evidence for J123652+621444 low surface brightness emission extending over 30-arcsec to the J123652+621444 east. If this is an extension to the core-jet structure seen in J123652+621444 the high-resolution MERLIN+VLA image, the jet has an overall J123652+621444 extent of 100kpc. The core overlies the nucleus of an I=18.5mag J123652+621444 elliptical galaxy on the HDF frame at a redshift of 0.321 J123652+621444 (Cowie et al., 2004, Cat. ). J123652+621444 It is detected by Chandra. J123653+621139 (starburst) has a steep spectrum (alpha>0.77). The radio J123653+621139 structure shows a compact component with a slight (0.3-arcsec) J123653+621139 extension to the east. The compact component overlies the J123653+621139 nucleus of an I=21.9mag compact galaxy at a redshift of 1.275 J123653+621139 (Cohen et al., 2000, Cat. ). It is also detected J123653+621139 by ISO at 15um with a flux density of 180uJy. J123653+621139 There is a faint Chandra counterpart. J123654+621040 (starburst candidate) has a steep spectrum (alpha>1.0) and is J123654+621040 extended over approximately 1.5-arcsec; it shows no signs of J123654+621040 compact emission at 0.2-arcsec resolution. The source lies close J123654+621040 to the edge of the HFF frame but there is no optical J123654+621040 identification at the radio source position brighter J123654+621040 than I=25mag. J123655+620917 (unclassified) has a radio spectrum with alpha>0.55. The source J123655+620917 contains a compact component associated with the galaxy nucleus J123655+620917 and emission extending over 0.6-arcsec. The compact component J123655+620917 overlies the nucleus of an I=20.4mag galaxy at a redshift of J123655+620917 0.419 (Cowie et al., 2004, Cat. ) J123655+620808 (unclassified) has a steep radio spectrum (alpha>0.85) and shows J123655+620808 a compact component with emission extending over 0.7-arcsec. The J123655+620808 radio source lies outside the CFHT image so no optical frame is J123655+620808 shown in Fig. C1. However, Cowie et al. (2004, J123655+620808 Cat. ) catalogue an R=22.6mag galaxy at the J123655+620808 position of the radio source with a redshift of 0.792. J123655+620808 There is a faint Chandra counterpart. J123656+621207 (starburst candidate) has a steep spectrum (alpha>1.32), is J123656+621207 extended over 1-arcsec and shows no sign of any compact emission J123656+621207 at 0.2-arcsec resolution. It lies close to the edge of an HDF J123656+621207 frame and at the radio position there is no optical object J123656+621207 brighter than I=28mag. Richards et al. (1999ApJ...526L..73R) J123656+621207 report that NICMOS imaging shows no counterpart to the limits J123656+621207 J>25 and H>25; Barger et al. (1999AJ....117..102B) J123656+621207 find no counterpart at K>24. The radio source is located J123656+621207 3-arcsec from the second brightest SCUBA source, HDF 850.2 J123656+621207 (Hughes et al. 1998Natur.394..241H), but the association is J123656+621207 uncertain - see the detailed discussion in Section 8.4.2 J123656+621301 (starburst) has a steep radio spectrum (alpha>1.22), is extended J123656+621301 over 1.2-arcsec and is identified with an I=22.5mag compact J123656+621301 galaxy at a redshift of 0.474 (Bauer et al. J123656+621301 2002AJ....123.1163B). It has an ISO counterpart and is detected J123656+621301 by Chandra. The bright companion galaxy to the south-east has a J123656+621301 redshift of 0.475 (Cohen et al., 2000, Cat. ). J123659+621449 (starburst candidate) is extended over 1.0-arcsec and shows no J123659+621449 sign of compact emission at 0.2-arcsec resolution. The radio J123659+621449 structure overlies a disturbed I=20.9mag disc galaxy at a J123659+621449 redshift of 0.761 (Cowie et al., 2004, Cat. ). J123659+621449 The galaxy appears to show a dust lane or double nucleus and may J123659+621449 be undergoing a merger. The source is detected by ISO and has J123659+621449 a faint Chandra counterpart. J123700+620909 (AGN candidate) has a steep radio spectrum (alpha=0.89). There is J123700+620909 a compact component with one-sided emission to the north-east; J123700+620909 the total angular size of the source being 0.4-arcsec. There is J123700+620909 no optical counterpart at the radio position to the limit J123700+620909 of I=25mag in the CFHT frame. J123701+621146 (starburst) has a steep radio spectrum (alpha=0.67) and is J123701+621146 extended over 3-arcsec in the VLA-only image at 2-arcsec J123701+621146 resolution (not shown). At 0.5-arcsec resolution some of the J123701+621146 outer low surface brightness emission is resolved out, but the J123701+621146 central 1.5-arcsec of emission is well imaged and shows no sign J123701+621146 of any compact component. There is no optical detection at the J123701+621146 radio position on the HFF frame brighter than I=25mag. The J123701+621146 source is detected by ISO. J123701+621146 is the most likely J123701+621146 radio counterpart to SCUBA 850.6 (see Section 8.4.5). J123701+621146 There is a faint Chandra counterpart. J123702+621401 (unclassified) has a steep radio spectrum (alpha>0.79) and is J123702+621401 extended over 3.4-arcsec in the VLA-only image (not shown). J123702+621401 At 0.5-arcsec resolution the source shows no sign of any compact J123702+621401 component and some of the low surface brightness emission is J123702+621401 resolved out. The south-eastern end of the source overlies an J123702+621401 I=21.9mag galaxy at a redshift of 1.2463 (Cowie et al., 2004, J123702+621401 Cat. ), with a significant fraction of the J123702+621401 extended emission lying well outside the confines of the optical J123702+621401 galaxy; the latter precludes a straightforward classification as J123702+621401 a starburst candidate. It is detected by ISO. J123704+620755 (starburst candidate) is extended over 1-arcsec and shows no sign J123704+620755 of any compact component. It is outside the CFHT frame but it J123704+620755 is detected by Chandra. J123705+621153 (starburst) has a steep spectrum (alpha>1.27) and is extended J123705+621153 over 1.5-arcsec with no evidence for any compact component J123705+621153 at 0.2-arcsec resolution. The source is centred on the nuclear J123705+621153 region of an I=20.6mag face-on spiral galaxy at a redshift J123705+621153 of 0.902 (Cowie et al., 2004, Cat. ). The source J123705+621153 is detected by ISO and has a faint Chandra counterpart. J123707+621408 (starburst candidate) has a relatively flat radio spectrum J123707+621408 (alpha=0.29). The source is extended over 0.9-arcsec and there J123707+621408 is no evidence for any compact component. The radio morphology J123707+621408 favours a starburst classification and the relatively flat J123707+621408 spectrum may be attributed to low-frequency free-free J123707+621408 absorption. There is no obvious optical identification on the J123707+621408 HFF frame although there does appear to be a faint I=24.9mag J123707+621408 galaxy at the radio position on the CFHT frame. Chapman et al. J123707+621408 (2004ApJ...611..732C) identify the system as a submillimetre J123707+621408 galaxy (S_850_=4.7+/-1.5mJy) with a redshift of 2.48. J123707+621408 It is detected by Chandra. J123707+621121 (starburst candidate) has a steep radio spectrum (alpha>0.82). J123707+621121 It is extended over 0.6-arcsec and there is no evidence for any J123707+621121 compact component. There is a faint I=25mag object at the J123707+621121 radio source position on the CFHT frame. J123708+621056 (starburst candidate) has a relatively flat radio spectrum J123708+621056 (alpha=0.35) but there is no evidence for any compact radio J123708+621056 component at 0.2-arcsec resolution. The radio spectrum may J123708+621056 therefore be due to substantial free-free absorption at 1.4GHz. J123708+621056 The source is extended over 0.7-arcsec and is displaced by J123708+621056 0.5-arcsec from the central region of an I=19.8mag edge-on disc J123708+621056 galaxy at a redshift of 0.422 (Cowie et al., 2004, J123708+621056 Cat. ). This separation is probably real since J123708+621056 the registration errors, even towards the edge of the HFF, are J123708+621056 substantially lower than 0.5-arcsec. J123708+621056 There is a faint Chandra counterpart. J123709+620837 J123709+620837/J123709+620841 (AGN and AGN candidate) are J123709+620837 separated by 4.5-arcsec. J123709+620837 has a flat radio J123709+620837 spectrum (alpha=0.35). J123709+620841 is undetected at 8.4GHz, J123709+620837 implying a steeper radio spectrum, although it is difficult to J123709+620837 separate these sources in the 8.4-GHz image where the angular J123709+620837 resolution is comparable to the source separation. They both J123709+620837 have compact cores and faint extended emission. The compact J123709+620837 component dominates the radio emission in J123709+620837, which J123709+620837 is unambiguously identified as an AGN system with a compact J123709+620837 flat-spectrum core. J123709+620841 may also be an AGN system, J123709+620837 although this is less clear. Each radio source is identified J123709+620837 with a separate galaxy [I=20.4 and 21.4mag with redshifts of J123709+620837 0.907 and 0.902 respectively (Cowie et al., 2004, J123709+620837 Cat. )]; in each case the compact radio J123709+620837 component overlies the nucleus of the galaxy. Both sources J123709+620837 have Chandra counterparts; J123709+620837 has the J123709+620837 brighter X-ray emission. J123709+620841 See J123709+620837 J123711+621330 (AGN candidate) has a steep radio spectrum (alpha=0.69). The J123711+621330 source contains a compact radio component with one-sided J123711+621330 jet-like emission extending ~1.2-arcsec to the east. The J123711+621330 compact component is coincident with the brightest part of an J123711+621330 I=22.7mag galaxy. The optical galaxy is asymmetric in the same J123711+621330 sense as the radio structure. Bauer et al. (2002AJ....123.1163B) J123711+621330 estimate a photometric redshift of 1.112 for this galaxy. The J123711+621330 classification as an AGN candidate is based on the registration J123711+621330 of the compact component with the bright optical nucleus J123711+621330 together with the asymmetry of the radio structure. The J123711+621330 associated X-ray emission detected by Chandra is significantly J123711+621330 offset by 0.9-arcsec to the east of the radio peak. J123711+621325 (starburst candidate) has a steep radio spectrum (alpha>1.16) and J123711+621325 extends over 0.8-arcsec, and shows no sign of compact emission J123711+621325 at 0.2-arcsec resolution. The source is identified with an J123711+621325 I=25mag galaxy on the CFHT frame. Chapman et al. J123711+621325 (2004ApJ...611..732C) identify the system as a submillimetre J123711+621325 galaxy (S_850_=4.2+/-1.3mJy) with a redshift of 1.99. J123711+621325 There is a faint Chandra counterpart. J123713+621603 (starburst candidate) is extended over 0.9-arcsec with no J123713+621603 evidence for any compact radio component at 0.2-arcsec J123713+621603 resolution. It is identified with an I=22.8mag galaxy on the J123713+621603 CFHT frame; the source overlies the nuclear region. J123714+621558 (starburst candidate) is extended over 1.5-arcsec with no sign of J123714+621558 any compact component at 0.2-arcsec resolution. The source is J123714+621558 identified with an I=20.8mag galaxy on the CFHT frame at a J123714+621558 redshift of 0.567 (Cohen et al., 2000, Cat. ). J123714+620823 (AGN) has an inverted radio spectrum (alpha=0.15) and the radio J123714+620823 structure is almost unresolved. The image shown in Fig. C1 and J123714+620823 described in Tables A1 and A2 is from the MERLIN data only. J123714+620823 It is identified with the nucleus of an I=22.0mag galaxy on J123714+620823 the CFHT frame. J123716+621643 (starburst candidate) is extended over 0.9-arcsec. The radio J123716+621643 emission overlies what appears to be a pair of merging galaxies J123716+621643 on the CFHT frame. The radio emission is offset from the J123716+621643 brighter galaxy by ~1-arcsec. This is real since the J123716+621643 registration errors in this region are <250mas. The brighter J123716+621643 galaxy has I=21.6mag and a redshift of 0.557 (Cohen et al., 2000 J123716+621643 Cat. ). There is a faint Chandra counterpart. J123716+621733 (AGN candidate) has a steep radio spectrum (alpha>0.76). The J123716+621733 radio structure contains a compact component with a 0.6-arcsec J123716+621733 one-sided extension to the south-west. The compact component J123716+621733 overlies the nucleus of an I=22.2mag galaxy with a redshift of J123716+621733 1.146 (Cowie et al., 2004, Cat. ). J123716+621733 It is detected by Chandra. J123716+621007 (starburst candidate) has emission extending over 0.7-arcsec. It J123716+621007 overlies the nucleus of an I=19.9mag galaxy at a redshift of J123716+621007 0.411 (Cohen et al., 2000, Cat. ). J123716+621007 There is a faint Chandra counterpart. J123717+620827 (starburst candidate) has a steep radio spectrum (alpha>0.77). J123717+620827 The radio structure is extended north-south over 2.1-arcsec. At J123717+620827 0.5-arcsec resolution some of the low surface brightness J123717+620827 emission is resolved out and there is no evidence for any J123717+620827 compact component. The brightest part of the radio structure J123717+620827 overlies the nuclear region of an I=19.7mag galaxy on the J123717+620827 CFHT frame. J123719+620902 (starburst candidate) is extended over ~0.7-arcsec and overlies J123719+620902 the nuclear region of an I=22.1mag galaxy on the CFHT frame. J123719+620902 This source is not listed in Richards (2000ApJ...533..611R). J123721+621129 (AGN) has an inverted spectrum (alpha=0.28) with a dominant J123721+621129 compact radio component and one-sided emission extending J123721+621129 ~0.8-arcsec to the north. This source is thus almost certainly J123721+621129 an AGN system. There is no optical identification at the radio J123721+621129 source position brighter than I=25mag. There is a distorted J123721+621129 disc galaxy to the north-east with an estimated photometric J123721+621129 redshift of 2.468 (Bauer et al. 2002AJ....123.1163B), but the J123721+621129 radio-optical offset of over 1-arcsec is far too high to be J123721+621129 accounted for by astrometric errors. Richards et al. J123721+621129 (1999ApJ...526L..73R) report that from deep I- and K-band J123721+621129 imaging (Barger et al. 1999AJ....117..102B), this radio source J123721+621129 is associated with a very red object with I-K>5.2. J123721+621129 There is a faint Chandra counterpart. J123721+621346 (starburst candidate) has a steep radio spectrum (alpha>0.66). J123721+621346 The radio structure is extended over 0.7-arcsec and shows no J123721+621346 evidence for any compact component at 0.2-arcsec resolution. The J123721+621346 source is identified with an I=22.1mag galaxy at a redshift of J123721+621346 1.019 (Cohen et al., 2000, Cat. ). J123725+620856 (unclassified) is extended over ~0.4-arcsec. It overlies the J123725+620856 nuclear region of an asymmetrical I=22.1mag galaxy, with an J123725+620856 estimated photometric redshift of 0.984 (Bauer et al. J123725+620856 2002AJ....123.1163B). It is detected by Chandra. J123725+621005 (unclassified) is extended over ~3.8-arcsec aligned roughly J123725+621005 east-west. There is no evidence for any compact component and at J123725+621005 0.2-0.5-arcsec angular resolution some of the low surface J123725+621005 brightness emission has been resolved out. The position given in J123725+621005 Table A1 is from the VLA-only image (not shown). The radio source J123725+621005 overlies the nuclear region of an I=19.1mag galaxy with an J123725+621005 estimated photometric redshift of 0.360 (Bauer et al. J123725+621005 2002AJ....123.1163B). J123725+621128 (AGN - WAT radio galaxy) has a steep radio spectrum (alpha=1.35). J123725+621128 The radio lobes extend over ~3.8-arcsec and are oriented J123725+621128 east-west. These lobes are characteristic of a classical J123725+621128 wide-angled-tail (WAT) radio structure. The radio core overlies J123725+621128 the nucleus of a compact, I=22.9mag galaxy. J123730+621258 (unclassified) has a steep spectrum (alpha>0.79) and contains a J123730+621258 compact radio component with extended emission over J123730+621258 ~0.3-arcsec. The object lies outside the area of the CFHT frame. J123732+621012 (unclassified) is extended over ~1.9-arcsec and contains no J123732+621012 compact component. The object lies outside the area of the CFHT J123732+621012 frame. The position given in Table A1 is from the J123732+621012 VLA-only image (not shown). J123734+620931 (unclassified) is extended over ~2.8-arcsec and contains no J123734+620931 compact component. The object lies outside the area of the CFHT J123734+620931 frame. The position given in Table A1 is from the VLA-only image J123734+620931 (not shown). There is a faint Chandra counterpart.