HCG 21

Deep Sky Object in Winter

HCG21 (Galaxy Group in Eridanus)

Date & Time:	Nov 13 2020, from 23:51 to 24:57 JST(+0900)
	Composed 12 shots with 6 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(4080×4080)
	Device Size...20×20mm
	Sensitivity...ISO4000, White Balance...Daylight

This picture shows you a galaxy group of the Hickson Compact Group (HCG) 21 that positions at about 50 arc minutes north of τ1 Eridani in the western region of the constellation. A border between the Cetus is crossing vertically in the center of the image. The brightest NGC1099 (HCG21A) is a 13th magnitude barred galaxy having a long axis of 2.5 arc minutes. Other four member galaxies lines up annularly in a span of 15 arc minutes. All of them are small-scaled galaxies with brightness of 13th to 14th magnitude. The distance to the group has been estimated as about 350 million light years.
Numbers with 4 digits represent NGC #

NGC1099 / Galaxy, type SB(rs)b
R.A.	02h 45m 17.9s (2000.0)
Dec.	-17°42' 30" (2000.0)
Apparent Size	2.5×0.8'
Radial Velocity	+7613km/s
Magnitude	13.1
Distance	357 million light yrs.
Group of Galaxies	-
Other IDs	ESO 546-15, Hickson 21A MCG -3-8-11, IRAS 2429-1754 PGC 10422

NGC1100 / Galaxy, type SAB(r)a:
R.A.	02h 45m 36.0s (2000.0)
Dec.	-17°41' 19" (2000.0)
Apparent Size	2.0×0.9'
Radial Velocity	+7554km/s
Magnitude	13.9
Distance	357 million light yrs.
Group of Galaxies	-
Other IDs	ESO 546-18, Hickson 21B MCG -3-8-16, PGC 10438

NGC1098 / Galaxy, type SA(s)0-:
R.A.	02h 44m 53.6s (2000.0)
Dec.	-17°39' 33" (2000.0)
Apparent Size	1.6×1.4'
Radial Velocity	+7387km/s
Magnitude	12.5
Distance	357 million light yrs.
Group of Galaxies	-
Other IDs	ESO 546-14, Hickson 21C MCG -3-8-8, PGC 10403

Abell 548

HCG23

			Copyright(c) 2020 by Naoyuki Kurita, All rights reserved.
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