The Project

The beginnings of this project precede my own interest.  Dr. Halton Arp attended the Texas Star Party in 1995. In the months leading up to the Star Party, my friend Dennis Webb became very interested in the Arp Peculiar Galaxy catalog and began to research it.  By May of 1995, in time for TSP and Dr. Arp's talk, he had reconstructed the catalog data, corrected an number of errors in identification and position, and assembled a 20-page booklet with lots of useful information for potential observers, visual or CCD.  Subsequently, he put that information and more on a web site.  He had started imaging the list and, in July 1995, at the Astronomical League convention in San Antonio, suggested the League add an Arp pin to their compliment of observing programs.  This was approved and the program was established shortly thereafter.  To receive this award, 100 of the Arp fields must be observed, either visually or with a CCD or film image.  Awards are designated as V or C, depending on nature of the observations.

Even though Dennis was a close friend and observing partner, I failed to share his initial enthusiasm.  In fact, I found the whole idea rather ridiculous.  Why waste time imaging tiny, faint objects when there are so many big, bright, showy ones?  My downfall came when I decided to take a shot of the Hercules galaxy cluster, Abell 2151.  There was nothing big or impressive in the image but there were dozens of tiny galaxies, and many that were quite unusual.  One in particular caught my attention and I showed it to Dennis.  His response was "Oh, that's Arp 71 and this other strange one is Arp 172."  I was hooked.  That image was taken on August 18, 2003, and I consider that the start date for this project.  However, I did "mine" my image files and discovered I had already imaged a few, like M32, M51, and M101, without realizing they were Arps, but those have all been replaced with better images.  Only two images taken prior to my start date are still included on this site -- Arp16 (M66) and Arp 152 (the Jet in M87).  I expect to eventually replace both of them.

As I began working toward my Arp pin, I did what most people do and started on the list of big and bright ones (relatively, at least) from Dennis' web site.  Meanwhile, Dennis and Jeff Kanipe began working with Willman-Bell on their book (see Links). My image count was in the 60's when Dennis began soliciting images (and imagers and visual observers) for the book.  The larger, brighter ones had mostly been done by imagers with better skills and equipment than mine but good images of the tiny and/or faint ones were scarce.  Since one image counted just like any other for the pin, I offered to go after the missing ones.  I completed my Arp 100 list on May 19, 2004, at the Texas Star Party but just kept going to help Dennis.  My count was close to 160 when Dennis' needs were met.  Since about 100 of mine were faint little pipsqueaks, I realized that the majority of the ones remaining were at least moderately big and bright.  It seemed like an enjoyable effort to go for the entire list.

The last image to reach my 338 was Arp 271, taken on May 24, 2006 -- it's shown to the left.  It was a great finish, as I consider it one of the most beautiful.  It was, however, one of my most challenging images because the wind was always above 15 mph, with 35 mph gusts.  I was only able to salvage 29 minutes of useful data out of the 79 minutes I imaged.

This project isn't really over and probably won't completely stop until the end of my imaging days.  Since completing the entire list, I've already either replaced or added integration time to 45 images that I didn't consider satisfactory.  There are another 30 or so that I've put a high priority on replacing, and even more that I'd like to replace when I get around to it.  Also, I plan to get back to color imaging and add color versions of some of the brighter Arps.  If you have the interest, check this site every few months to see what has been added or improved. 

My original goal was to accumulate at least an hour of integration on every object.  I stuck with that for a while but realized the project was going to take forever.  The majority of my images reflect a total integration of 20 to 40 minutes.  Also, to complete a project of this magnitude in a reasonable amount of time, I found I couldn't be too picky about conditions.  While all images were done at dark sky locations, I did not let wind, slight haze, a few thin clouds, or a modest amount of moonlight interfere.

For the statistically minded, here are a few data points for the initial set of 338.  These numbers would change as I reimage things but I don't intend to keep revising them:

                  Elapsed time, start to finish                            2 years, 9 months, 6 days
                  Average number per month                                              10.2

                  Average integration time                                Mean = 31.8 min., Mode = 28 min.
                  Shortest image                                                  Arp 152 (Jet in M87), 22 sec.
                  Longest image                                                            Arp 174, 84 min.

                  Taken at West Point, TX                                                      305
                  Taken at Texas Star Party                                                     30
                  Taken at Fort McKavett, TX                                                     3

                  10-inch Newtonian images                                                   296
                  Celestron CG9 1/4 images                                                    33
                  Meade 2045D images                                                            9

                  Cookbook 245 images                                                          34
                  Cookbook plus StarlightXpress MX716 images                         1
                  StarlightXpress MX716 images                                            283
                  StarlightXpress MX719 plus MX916 images                              3
                  StarlightXpress MX916 images                                              17

Even though I had been imaging for almost eight years when this project started, the intensity of the effort resulted in a major improvement in the quality of my images.  Part of it was equipment, such as the addition of an NGF focuser with Motofocus and the camera upgrade from the Cookbook 245 to the StarlightXpress MX716.  But the best of the Cookbook images are very competitive -- see the Arp 154 image page.  Software was important because Astroart 3.0 has a much better focus routine than my Cookbook software.  MX716 selfguiding was more precise than my ST-4 autoguiding, mainly because it is almost impossible to eliminate every trace of differential flex between two optical systems.  But by far the most important factor was simply the increase in my skill and attention to detail.  I check my collimation frequently and don't accept it if it isn't perfect.  I check the mechanics of the system every few nights, making sure nothing has loosened, shifted, overtightened, etc.  I spend a LOT more time making sure my focus is as precise as possible and I recheck it at least between each set of images, and part way through a set if the set is long or the temperature is changing quickly.  I take a lot of flats, darks, and biases, and check them to make sure there are no imperfections before I use them.  Both of the pictures above were taken with the MX716 camera, the left one late in 2003 and the right one in early 2006.  Everything was wrong with the one on the left.  Collimation and focus were poor, there was some looseness in my guidescope attachment, I didn't take enough darks, and took no flats or bias frames.  None of those problems existed when I took the one on the right.  The great difference in quality is obvious.