J/A+A/661/A85 Asteroid trails in HST images (Kruk+, 2022)
Hubble Asteroid Hunter.
I. Identifying asteroid trails in Hubble Space Telescope images.
Kruk S., Garcia Martin P., Popescu M., Merin B., Mahlke M., Carry B.,
Thomson R., Karadag S., Duran J., Racero E., Giordano F., Baines D.,
de Marchi G., Laureijs R.
<Astron. Astrophys. 661, A85 (2022)>
=2022A&A...661A..85K 2022A&A...661A..85K (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets ; Positional data
Keywords: minor planets, asteroids: general -
astronomical databases: miscellaneous - methods: data analysis
Abstract:
Large and publicly available astronomical archives open up new
possibilities to search and study Solar System objects. However,
advanced techniques are required to deal with the large amounts of
data. These unbiased surveys can be used to constrain the size
distribution of minor bodies, which represents a piece of the puzzle
for the formation models of the Solar System.
We aim to identify asteroids in archival images from the ESA Hubble
Space Telescope (HST) Science data archive using data mining.
We developed a citizen science project on the Zooniverse platform,
Hubble Asteroid Hunter (www.asteroidhunter.org) asking members of the
public to identify asteroid trails in archival HST images. We used the
labels provided by the volunteers to train an automated deep learning
model built with Google Cloud AutoML Vision to explore the entire HST
archive to detect asteroids crossing the field-of-view.
We report the detection of 1701 new asteroid trails identified in
archival HST data via our citizen science project and the subsequent
machine learning exploration of the ESA HST science data archive.We
detect asteroids to a magnitude of 24.5, which are statistically
fainter than the populations of asteroids identified from ground-based
surveys. The majority of asteroids are distributed near the ecliptic
plane, as expected, where we find an approximate density of 80
asteroids per square degree. We match 670 trails (39% of the trails
found) with 454 known Solar System objects in the Minor Planet Center
database, however, no matches are found for 1031 (61%) trails. The
unidentified asteroids are faint, being on average 1.6 magnitudes
fainter than the asteroids we succeeded to identify. They probably
correspond to previously unknown objects.
Citizen science and machine learning are very useful techniques for
the systematic search of Solar System objects in existing astronomy
science data archives. This work describes a method to find new
asteroids in astronomical archives spanning decades in time, which
could be effectively applied to other datasets, increasing the overall
sample of well characterised small bodies in the Solar System and
refining their ephemerides.
Description:
We present a sample of asteroids trails identified in almost two
decades of Hubble Space Telescope observations with crowdsourcing in
the Hubble Asteroid Hunter citizen science project and using the
AutoML deep learning object detection algorithm on Google Cloud (see
paper). The table provides the IDs, instruments, filters of the HST
observations with asteroid trails, the observation times and positions
of the trails, and the measured trail lengths and magnitudes for 1701
trails. 670 trails were matched with known SSOs in the Minor Planet
Center database; the identified corresponding asteroids are shown in
the table, otherwise, blank indicates unidentified objects. A preview
of the table is shown in Appendix A of the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 214 1701 Asteroid trails identified in the Hubble
Space Telescope observations
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See also:
www.asteroidhunter.org : Hubble Asteroid Hunter Home Page
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- ObjectID Unique ID made of seven digits assigned for
each of the reported trails, AHNNNNN
(Object_ID)
9- 17 A9 --- HSTobsID Image ID corresponding to the composite HST
image where the trail was identified
(HSTobservationID)
19- 27 A9 --- Inst HST Instrument and Aperture (Instrument)
29- 36 A8 --- Filter HST Filter (Filter)
38 I1 --- Nex Number of trail segments, corresponding of
the number of individual exposures where
the SSO was identified (N_ex)
40- 52 F13.7 d MJDsTrail Modified Julian day at the start of the
individual exposure where the trail was
first identified (MJDstarttrail)
54- 66 F13.7 d MJDeTrail Modified Julian day at the end of the
individual exposure where the trail was
last identified (MJDendtrail)
68- 80 F13.7 d MJDsExp Modified Julian day at the start of the
first exposure used to obtain the
composite image (MJDstartexp)
82- 94 F13.7 d MJDeExp Modified Julian day at the end of the last
exposure used to obtain the composite image
(MJDendexp)
96-102 F7.1 s TrailExp Total exposure time for the trail, obtained
as the sum of exposure times of all
individual exposures in which the trail
was identified (Trail_Exp)
104-114 F11.7 deg RAsdeg Right ascension of the first pixel of the
trail at Ep=MJDsExp (RA_start) (1)
116-126 F11.7 deg DEsdeg Declination of the first pixel of the
trail at Ep=MJDsExp (DEC_start) (1)
128-138 F11.7 deg RAedeg Right ascension of the last pixel of the
trail at Ep=MJDeExp (RA_end) (1)
140-150 E11.7 deg DEedeg Declination of the last pixel of the trail
at Ep=MJDeExp (DEC_end) (1)
152-157 F6.2 arcsec TrailLength The total trail length between the first and
the last pixel of the trail (Trail_Length)
159-167 F9.4 e-/s TotalFlux The total flux obtained as the sum of all
pixels belonging to trail, given in the
default units of the HST images,
electrons/sec (Total_Flux)
169-174 E6.4 e-/s e_TotalFlux The total flux error, given in the default
units of the HST images, electrons/sec
(TotalFluxErr)
176-179 F4.1 mag Obsmag The calibrated magnitude derived from the
total flux in the filter used for the
observation (Observed_Mag)
181-190 A10 --- IdentObj The designation of the identified asteroid
(the asteroid number is given when this is
available, otherwise its temporary
designation is given) (Identified_Obj)
192-196 F5.3 arcsec O-C ?=- The difference between the observed
positions by HST and the computed positions
(obtained using the JPL Horizons system)
for the identified object (OminusC)
198-209 A12 --- OrbClass The orbital class of the object following
The Virtual Observatory Sky Body Tracker
(SkyBoT) definitions (Orbital_Class) (2)
211-214 F4.1 mag Predmag ?=- Predicted magnitude based on SkyBoT
query (Predicted_Mag)
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Note (1): The terms 'first pixel' and 'last pixel' are considered with respect
to an unspecified direction of motion of the asteroid.
Note (2): The Virtual Observatory Sky Body Tracker (SkyBoT),
http://vo.imcce.fr/webservices/skybot/?documentation
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Acknowledgements:
Sandor Kruk, kruksandor(at)gmail.com
(End) Sandor Kruk [MPE], Patricia Vannier [CDS] 13-Apr-2022