HCG 31

Deep Sky Object in Winter

HCG31 (Galaxy Group in Eridanus)

Date & Time:	Nov 28 2021, from 22:21 to 23:05 JST(+0900)
	Composed 12 shots with 4 minutes exposed
Optical:	Meade 25cm(10") Schmidt-Cassegrain with conversion lens (f=1600mm, F6.3)
	with BaaderPlanetarium Moon&Skyglow filter
	Auto-guided with Meade LX200 Equatorial & Lacerta M-GEN
Digital Camera:	Nikon D810A
Location:	Ooizumi, Hokuto city, Yamanashi pref.

Camera Settings:	Recording Format...14bit CCD-RAW, converted to 16bit TIFF(2040×2040)
	Device Size...10×10mm
	Sensitivity...ISO4000, White Balance...Daylight

At the northeast edge of Eridanus, this image shows you the Hickson Compact Group 31 positioned at 1.8 degrees northwest of β Eri. The galaxy group contains four small members just touching with sizes of about an arc minute and brightness of 13th to 15th magnitude. The largest one of HCG31A (NGC1714) has a largely distorted shape; the star burst region has been distributed in intergalactic space. The group has a span of approx. 150 thousand light years, and the distance is estimated as approx. 150 million light years.

NGC1741 / Galaxy, type Pec
R.A.	05h 01m 38.6s (2000.0)
Dec.	-04°15' 32" (2000.0)
Apparent Size	0.9×0.3'
Radial Velocity	+4004km/s
Magnitude	13.3
Distance	150 million light yrs.
Group of Galaxies	-
Other IDs	Arp 259, Hickson 31A MCG -1-13-45, IRAS 4591-419 PGC 165745

Hickson 31B / Galaxy, type SB(s)m pec sp
R.A.	05h 01m 35.4s (2000.0)
Dec.	-04°15' 49" (2000.0)
Apparent Size	0.7×0.3'
Radial Velocity	+4117km/s
Magnitude	15.2
Distance	150 million light yrs.
Group of Galaxies	-
Other IDs	PGC 16570

Hickson 31C / Galaxy, type SB(s)m pec:
R.A.	05h 01m 38.0s (2000.0)
Dec.	-04°15' 30" (2000.0)
Apparent Size	0.7×0.4'
Radial Velocity	+4068km/s
Magnitude	13.3
Distance	150 million light yrs.
Group of Galaxies	-
Other IDs	PGC 165737

HCG23

M35

			Copyright(c) 2021 by Naoyuki Kurita, All rights reserved.
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