Morphological classifications of about 20k galaxies from Tanaka et al. 2023 are now publicly available. The catalog is based on citizen scientists' classifications collected during the 1st season of GALAXY CRUISE (November 2019 -- April 2022). The targets are bright galaxies with spectroscopic redshifts from SDSS or GAMA and they are classified on high-quality, deep images from the Hyper Suprime-Cam Subaru Strategic Program Public Data Release 2 (HSC-SSP PDR2). For details of the target selection as well as the morphological classification scheme, the user is referred to the paper. HSC-SSP PDR2 is described in depth in Aihara et al. 2019 and also at the data release site.
 
The catalog is available here (2.3 MB). The meaning of each column is as follows. Please cite Tanaka et al. 2023 if you use the catalog in your publication.
 

column   no.	name	note
1	object_id	HSC PDR2
2	R.A.	[deg] J2000
3	Dec.	[deg] J2000
4	specz	either from SDSS or GAMA
5	zcmodel_mag	from HSC PDR2
6	tract	from HSC PDR2
7	patch	from HSC PDR2
8	layer	Wide or D/UD
9	num_class	total number of classifications made for this object
10	galaxy_type	P(spiral)_corr
11	interaction	P(interaction)_corr
12	ring	P(ring) -- see note
13	fan	P(fan) -- see note
14	tail	P(tail) -- see note
15	distortion	P(distortion) -- see note
16	valid_frac(galaxy_type)	see note
17	valid_frac(interaction)	see note
18	specObjID	either from SDSS or GAMA
19	R.A.	[deg] J2000 from spectroscopic catalog
20	Dec.	[deg] J2000 from spectroscopic catalog
21	MJD	available only for SDSS. "null" for GAMA
22	plate	available only for SDSS. "null" for GAMA
23	fiberID	available only for SDSS. "null" for GAMA
24	z	either from SDSS or GAMA (should be identical to column #4)
25	zErr	available only for SDSS. "null" for GAMA
26	class	available only for SDSS. "null" for GAMA
27	zWarning	redshift flag
28	legacyPrimary	available only for SDSS. "null" for GAMA
29	dered_u	dereddened u-band modelMag
30	dered_g	dereddened g-band modelMag
31	dered_r	dereddened r-band modelMag
32	dered_i	dereddened i-band modelMag
33	dered_z	dereddened z-band modelMag

 
NOTES

• Various cleaning and corrections have already been applied to the classifications. To be specific, less accurate classifiers are removed, and the depth and redshift corrections are applied.
• columns 6-7: tract and patch are areal units used in HSC-SSP. Refer to Aihara et al. 2018 for details.
• columns 10-11: these are based on the first and second questions in GALAXY CRUISE. P(spiral)_corr larger than 0.79 yields a reasonably clean sample of spiral galaxies. We do not yet have a good threshold for interaction, but P(interaction)_corr larger than 0.79 is tentatively used in the paper.
• columns 12-15: these are based on the third question. Note that the fractions are normalized such that P(ring) + P(fan) + P(tail) + P(distortion) = 1. Recall that multiple features can be selected in the third question.
• columns 16-17: the answers to the first two questions of GALAXY CRUISE include the "not sure" option. This is intended for objects like strongly distorted interacting galaxies for which the original morphology is difficult to infer, or objects are too close to nearby bright star and classification is difficult, etc. Most people did not choose "not sure", and the "not sure" votes are excluded from columns 10-11 as discussed in the paper. The valid fraction here gives the fraction of people who voted for yes/no (or elliptical/spiral). In other words, 1-valid_frac gives the fraction of people who vote for "not sure". Those who interested in the violent mergers may want to look at objects 1 - valid_frac larger than 0.2. Note that a small fraction of them are galaxies located in/close to image artifacts for which classifications are difficult to make, and they have to be visually removed. For visual checks, we recommend hscMap available at the HSC-SSP data release site.
• columns 29-33:14 objects do not have SDSS photometry from DR15, while they do have spectra.

 

1. "Galaxy Cruise: Deep Insights into Interacting Galaxies in the Local Universe" Tanaka, M., et al. 2023, PASJ, 75, 986
2. A Joint Team of Astronomers and Citizen Astronomers Addresses Mysteries of Galaxies! (Subaru Telescope Science Results on October 9, 2023)
3. First Scientific Results from GALAXY CRUISE (NAOJ Science on October 10, 2023)
 

This work would not have been possible without a large number of citizen scientists (Citizen Astronomers). We appreciate their contributions and their names are listed in this page.
This work was financially supported by JSPS KAKENHI Grant Number 22H01270.