J/other/SAAOC/15.30 DDO photometry of E-region stars (Cousins 1993)
DDO photometry of E-region stars and equatorial standards (Paper I).
Cousins A.W.J.
<South Afr. Astron. Obs. Circ. 15, 30 (1993)>
=1993SAAOC..15...30C 1993SAAOC..15...30C (SIMBAD/NED BibCode)
ADC_Keywords: Photometry, DDO
Abstract:
This paper describes the observations and gives the results of a
series of observations of bright E-region stars (Cousins A.W.J. and
Stoy R.H., 1962RGOB...49....3C 1962RGOB...49....3C) for use as zero point stars for DDO
photometry in the southern hemisphere. The list comprises 45 stars,
all brighter than V=6.0, and gives the colours in the instrumental
system with internal s.e. ±0.001mag and m48 with s.e. ±0.002mag.
The observed m48 is indistinguishable from McClure's system and has
the same zero point (±0.002mag). The individual E-region zero points
have been established with s.e. ±0.001 relative to the instrumental
system, but the colour equations (and zero point corrections) to
transform the instrumental colours to McClure's system have still to
be finalised.
For a description of the DDO photometric system, see e.g. GCPD/12
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1 87 20 Observed and computed zero point differences
table2 101 9 Zero point errors
table3 43 45 DDO photometry of E region stars (Colours in
the instrumental system)
table1a 65 30 Transmissions of DDO filters used at Cape Town
table2b 13 40 B-V and m48-V colours
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Group [ab] Group
2- 6 A5 --- E E-regions (1)
8- 11 F4.1 mmag Obs35 Observed zero point differences in C(35-38)
13- 16 F4.1 mmag Cor35 ? Corrected zero point differences in C(35-38)
18- 21 F4.1 mmag Comp35 ? Computed zero point differences in C(35-38)
23- 27 F5.1 mmag Obs38 Observed zero point differences in C(38-41)
29- 33 F5.1 mmag Cor38 ? Corrected zero point differences in C(38-41)
35- 39 F5.1 mmag Comp38 ? Computed zero point differences in C(38-41)
42- 45 F4.1 mmag Obs41 Observed zero point differences in C(41-42)
47- 50 F4.1 mmag Cor41 ? Corrected zero point differences in C(41-42)
52- 55 F4.1 mmag Comp41 ? Computed zero point differences in C(41-42)
58- 61 F4.1 mmag Obs42 Observed zero point differences in C(42-45)
63- 66 F4.1 mmag Cor42 ? Corrected zero point differences in C(42-45)
68- 71 F4.1 mmag Comp42 ? Computed zero point differences in C(42-45)
74- 77 F4.1 mmag Obs45 Observed zero point differences in C(45-48)
79- 82 F4.1 mmag Cor45 ? Corrected zero point differences in C(45-48)
84- 87 F4.1 mmag Comp45 ? Computed zero point differences in C(45-48)
--------------------------------------------------------------------------------
Note (1): For each group, the region labelled Total indicates the total
observed zero point differences in each colours
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 I1 --- E E-region number
3- 6 F4.1 mmag zpe135 Zero point error for adjacent regions in C(35-38)
8- 11 F4.1 mmag zpe235 Zero point error for alternate regions in C(35-38)
13- 16 F4.1 mmag zpeM35 Means zero point error in C(35-38)
18- 21 F4.1 mmag zpeR35 Revised means zero point error in C(35-38)
23- 26 F4.1 mmag zpe138 Zero point error for adjacent regions in C(38-41)
28- 31 F4.1 mmag zpe238 Zero point error for alternate regions in C(38-41)
33- 36 F4.1 mmag zpeM38 Means zero point error in C(38-41)
38- 41 F4.1 mmag zpeR38 Revised means zero point error in C(38-41)
43- 46 F4.1 mmag zpe141 Zero point error for adjacent regions in C(41-42)
48- 51 F4.1 mmag zpe241 Zero point error for alternate regions in C(41-42)
53- 56 F4.1 mmag zpeM41 Means zero point error in C(41-42)
58- 61 F4.1 mmag zpeR41 Revised means zero point error in C(41-42)
63- 66 F4.1 mmag zpe142 Zero point error for adjacent regions in C(42-45)
68- 71 F4.1 mmag zpe242 Zero point error for alternate regions in C(42-45)
73- 76 F4.1 mmag zpeM42 Means zero point error in C(42-45)
78- 81 F4.1 mmag zpeR42 Revised means zero point error in C(42-45)
83- 86 F4.1 mmag zpe145 Zero point error for adjacent regions in C(45-48)
88- 91 F4.1 mmag zpe245 Zero point error for alternate regions in C(45-48)
93- 96 F4.1 mmag zpeM45 Means zero point error in C(45-48)
98-101 F4.1 mmag zpeR45 Revised means zero point error in C(45-48)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Star E-region star name
6- 10 F5.3 mag C(45-48) C(45-48) colour
12- 17 F6.3 mag C(42-45) C(42045) colour
19- 23 F5.3 mag C(41-42) C(41-42) colour
25- 30 F6.3 mag C(38-41) C(38-41) colour
32- 36 F5.3 mag C(35-38) C(35-38) colour
38- 42 F5.3 mag m48 ? m48 magnitude
43 A1 --- n_m48 [Vm] Note for variable stars (1)
--------------------------------------------------------------------------------
Note (1): Six stars are variable in light. A 'm' indicates mean magnitudes
for two stars with small ranges. E542 is an EA type star and the
maximum magnitude is given. A 'V' indicates other variables.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1a
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.1 nm W35 ? Wavelength in 35 filter
7- 10 F4.1 % T35 ? Transmition in 35 filter
12- 16 F5.1 nm W38 Wavelength in 38 filter
18- 21 F4.1 % T38 Transmition in 38 filter
23- 27 F5.1 nm W41 ? Wavelength in 41 filter
29- 32 F4.1 % T41 ? Transmition in 41 filter
34- 38 F5.1 nm W42 ? Wavelength in 42 filter
40- 43 F4.1 % T42 ? Transmition in 42 filter
45- 49 F5.1 nm W45 ? Wavelength in 45 filter
51- 54 F4.1 % T45 ? Transmition in 45 filter
56- 60 F5.1 nm W48 ? Wavelength in 48 filter
62- 65 F4.1 % T48 ? Transmition in 48 filter
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2b
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.2 mag B-V B-V colour index
7- 12 F6.3 mag m48-V m_48-V colour index
--------------------------------------------------------------------------------
Table 1b. Effective Wavelengths, Widths and Second Moments of DDO Filters
-------------------------------------------------------------------------
Cousins
-------------------------------------------------------------------------
lambdam (nm) 353.1 381.6 416.4 425.8 452.1 488.0
FWHM (nm) 28.0 28.7 7.6 7.9 6.8 18.3
mu2 (nm) 9.75 10.52 2.80 2.70 2.23 6.16
-------------------------------------------------------------------------
McClure's "Yale" filters
-------------------------------------------------------------------------
lambdam (nm) 347.4 382.3 416.4 425.6 452.1 488.3
FWHM (nm) 37.2 33.0 8.0 7.1 7.3 18.6
mu2 (nm) 12.35 11.40 2.58 2.31 2.36 6.28
-------------------------------------------------------------------------
John Caldwell has computed a polynomial transformation to derive m-V from
(B-V-0.800), and finds that the following coefficients give a good fit.
(Zero order is the constant term).
------------------
Order Coefficient
------------------
0 0.2960158
1 0.3250211
2 0.1475044
3 - 0.0216403
4 - 0.0875551
5 0.3587868
6 0.0220998
7 -0.2140784
------------------
Table2b may be useful when a few stars are involved.
-------------------------------------------------------------------------
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 28-Jan-1997