Matt; I am in agreement with AJ, I think that the number of evenings that I = have had truly excellent seeing in my backyard is about 5 nights and almost = never for the entire night, more like an hour or two. So, I think spending a = lot of money on a long focal length imaging system that you will be using = inside the city is a waste. I would think that either a refractor of 700mm or less, or using the Hyperstar system would provide better results. My opinion, but I have a lot of nights in my observatory when trying to = split anything less than 2 arcsec is just not possible at any magnification. Hope that helps; Steve Coe -----Original Message----- From: az-observing-bounce@xxxxxxxxxxxxx [mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of Matt Sent: Sunday, May 20, 2007 9:17 PM To: az-observing@xxxxxxxxxxxxx Subject: [AZ-Observing] Re: FWHM measurements for Phoenix skies, anyone? AJ, It seems from my research that, for imaging, anything sub 2 arcsec (as measured during critical automated focusing, I think) is considered very good to excellent. I wonder how often we get that here with our low humidity. BUT, turbulence from the giant urban heat island we live in = may offset our "Arizona Skies." I am planning on doing some patio imaging. It can be done RGB with an = LP filter or by going narrowband (O3, Ha, S2). My choice of scope and = camera may be influenced by the typical local seeing, but I just don't know = enough yet to make an educated decision. The monetary investment is = substantial, so I am trying to figure out as much as possible in advance. Matt -----Original Message----- From: az-observing-bounce@xxxxxxxxxxxxx [mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of AJ Crayon Sent: Sunday, May 20, 2007 9:01 PM To: az-observing@xxxxxxxxxxxxx Subject: [AZ-Observing] Re: FWHM measurements for Phoenix skies, anyone? Matt, this will, probably, generate, quite a bit of discussion. I = haven't=20 done anything scientific to answer your question, but I do have quite a = bit=20 of experience observing from my back yard, near 35th Ave and Thunderbird = Rd. Over the years the closes double that I remember splitting with my 8"=20 telescopes is 3". When I say my 8" telescopes that means the f6 = Newtonian=20 that I owned for about 20 years. It also references the new SCT = purchased=20 around the beginning of this year. The 3" split was not something that=20 could be done on a consistent basis, only if the observing conditions = were=20 good. My guess as to why, over 20 years, this kind of observing didn't = deteriorate is because most of the urban sprawl was north of my position. Most of = my=20 observing is to the south or west, the east being right smack dab into=20 Aurora Phoenicis. Any reason for settling on the 2+ arc seeing condition? Hope this helps, aj ----- Original Message -----=20 From: "Matt" <mluttinen@xxxxxxxxx> To: "'AZ-Observing mailing list'" <az-observing@xxxxxxxxxxxxx> Sent: Sunday, May 20, 2007 8:25 PM Subject: [AZ-Observing] FWHM measurements for Phoenix skies, anyone? Hello, Anyone (crazy enough) out there do enough urban imaging to get a feel = for an average FWHM over Phoenix? Is it usually 2+ arcsec (or worse) or do we sometimes get below that? I am about to jump off the imaging cliff and want to know what I am in = for. TYIA, Matt No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.467 / Virus Database: 269.7.6/813 - Release Date: 5/20/2007 7:54 AM -- See message header for info on list archives or unsubscribing, and = please send personal replies to the author, not the list. -- See message header for info on list archives or unsubscribing, and = please=20 send personal replies to the author, not the list. No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.467 / Virus Database: 269.7.6/813 - Release Date: 5/20/2007 7:54 AM =20 No virus found in this outgoing message. Checked by AVG Free Edition.=20 Version: 7.5.467 / Virus Database: 269.7.6/813 - Release Date: 5/20/2007 7:54 AM =20 -- See message header for info on list archives or unsubscribing, and = please=20 send personal replies to the author, not the list. -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.