NGC 3445 and NGC 3440 (UGC 6021, Arp 24 and UGC 6009) Galaxies in Ursa Major

Center of field located at approximately: RA 10 hours 54 minutes 18 seconds, Dec +57 degrees 03 minutes 59 seconds

Size: 1.6' x 1.4' and 2.6' x 0.7' Magnitude: 12.9 blue and 14.0 photographic Class: SAB(s)m and SBb? sp

North is up

West to the right


 14.5" f5 Newtonian reflector


 ST-8XME, self-guided, binned 1x1, temp -20c, camera control MaxIm DL 4.56


Lumicon Red filter, 500 minutes (50 x 10 minute subs), 02/25 & 03/15/2018; seeing 2.5-5.0 per CCDStack


CCDStack 2.94.6355.18107, Photoshop CS5.1


 Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s)


I started this field at the end of February, with a lot of moon in the sky. Then clouds set in, and then I took week of vacation in early March. When I returned, I had to wait for a night (3/15) of clear weather. Now it's cloudy again until the end of the week. I really need one more clear, moonless night on this field, but I am posting what I have for now. NGC 3445 (Arp 24) is the more interesting galaxy in the southeast, with NGC 3440 to the NNW (upper right).

From the NGC / IC Project:

NGC 3445 = Arp 24 = VV 14a = UGC 6021 = MCG +10-16-023 = CGCG 291-011 = PGC 32772

10 54 35.9 +56 59 24

V = 12.6;  Size 1.6'x1.5';  Surf Br = 13.4

48" (5/16/12): bright, moderately large, very irregular shape, roughly 1.2' diameter.  The brightest portion of the galaxy is on the north and east side and is very mottled with slightly brighter knots (a couple are on the east end).  Attached on the west side and spreading further south is a spiral arm, appearing more like a diffuse extension.  This "arm" fades out on the southeast side of the galaxy and just beyond is MCG +10-16-24, 1.2' SE of center.  This interacting companion appeared faint to fairly faint, elongated 5:2 E-W, 20"x8".  2MASX J10544552+5659588 lies 1.5' ENE, between the main galaxy and a mag 10.3 star just 2.2' NE of NGC 3445.  It appeared faint, very small, round, 12" diameter.  The bright star detracted somewhat from viewing the fainter companions.

17.5" (3/12/88): fairly bright, moderately large, slightly elongated WNW-ESE, broad concentration, bright core.  Located 2.2' SW of a mag 10 star.  Brightest in a group with NGC 3458 13.9' NE.

William Herschel discovered NGC 3445 = H I-267 = h787 on 8 Apr 1793 (sweep 1038) and recorded "cB, pL, iR, about 1 1/4' dia.  The greatest part of it almost equally bright." JH described "pB; L; R; vglbM; has a star 10m 2' nf."  His position is accurate.

R.J. Mitchell, observing with LdR's 72" on 30 Mar 1856, recorded "[NGC 3445] is very curious, it is round with bright nucleus excentric and a dark curved passage sp this nucleus as in sketch.  [See Plate III, fig 6].  The neby outside this dark curve runs up perhaps to a streak sf which is vF, but of the existence of which I have doubt."  The "streak south-following", which was displayed on the sketch, is certainly MCG +10-16-024 = PGC 32784.  It was mentioned again in the 3 Apr 1858 observation as "a vF, S patch of neby sf."


NGC 3440 = UGC 6009 = MCG +10-16-019 = CGCG 291-009 = PGC 32714

10 53 49.6 +57 07 08

V = 13.2;  Size 2.1'x0.5';  Surf Br = 13.1;  PA = 48d

17.5" (3/12/88): fairly faint, small, very elongated SW-NE, small bright core.  Forms a pair with NGC 3445 10.0' SE.

William Herschel discovered NGC 3440 = H III-914 = h785 on 8 Apr 1793 (sweep 1038) and noted "vF, S, lE."  JH gave no description, but his position matches UGC 6009.