NGC 3432 - Arp 206


Object: NGC 3432 galaxy in Leo Minor, also known as Arp 206 which is classified as "Material ejected from nuclei". English et al. [1] suggest an interaction between the two galaxies in the field is responsible for the extra planar features in NGC 3432 as well as an extended radio continuum halo. If their hypothesis is true then it seems that the uncertainties on the distance measurements are understated, otherwise 1-2 Mpc is long way between interacting galaxies. See NGC 3445 for another case of seemingly interacting galaxies at inconsistent redshifts.

The image was acquired only 3 months after receiving a new Losmandy G11 mount which had tracking problems out of the box, this is apparent in the trailed stars even though the autoguider was correcting the mount every 0.5 seconds. Over the rest of that spring the problem was corrected mechanically.

Data for the 2 galaxies in the field (center and bottom right):
NGC 3432 11.1m 6.6' x 1.6', type SB(s)m LINER HII, distance 12 +/- 0.9 Mpc
PGC 32617 15.3m 4.6' x 2.9', type Irr dwarf, distance 14 +/- 1 Mpc

Calibration: 3 darks
Subimages: 12 x 300 sec (1 hr), ISO 800, Input FWHM 4-5" (not optimally focussed)
Scope: C11XLT with RLS6.5FR, EFL=1912mm (f/6.8 effective)
Mount: Losmandy G11 with Gemini L3
Camera: Canon Eos 350D (0.69"/pixel) oriented at 13d20' (N up, E left)
Guiding: ST7EI, exposure time 0.5 sec.
Acquisition and Processing: MaxIm DL/CCD v4.5
Imaged on: March 26, 2006
Processed on June 29, 2007 !

Processing Log:
Convert from RAW to RGB: R=194%, G=100%, B=135%, auto bgd
Combine: Average with auto star matching align
Clone: Cloned out hot pixels, two sessions, major work.
Filter: Kernel filter LowPassMore with range restriction 0 to 190 ADU, ReduceRadius=10, FeatherDistance=20
Crop: Crop to 1000x1000 to get rid of huge reflection arc on left side and nasty bgd step at bottom 1/3 of frame.
Flatten Bgd: Split tricolor and performed auto gradient to each color channel, color stack to recombine.
Color Balance: Scale R:80% G:85% B:120%, BgdLevel R:164, G:162, B:168
Filter: Again Kernel LowPassMore, all pixels.
Resize: From 1000x1000 to 800x800

Images of this object are hard to come by, the few links I could find:
Image at http://www.ghg.net/akelly/ or Thumbnail and description (over 30 hrs data from the US Naval observatory!)
http://www.astrophotos.net/
http://www.3towers.com/sGrasslands/
http://338arps.com/


Reference 1: The Ionized Gas and Radio Halo of NGC 3432 (ARP 206) by Jayanne English and Judith A. Irwin published in the Astronomical Journal v.113, p. 2006-2024 (1997).