Starwiz

Thanks. I think my next hurdle is to get the tracking working better, although I'm not sure how just yet. More clear skies forecast here in Malta for the next several days, so I'll be having another play. 😀 John

Thanks Doug. I can't imagine the light pollution is great anywhere in Liverpool (I grew up in Birkenhead), so narrowband is a great way to go, and imaging when the moon is out will make full use of those precious clear skies up there. There's a great thread on Cloudy Nights about exposures for the ASI1600mm, in case you've not seen it. It addresses the question of minimum exposure to overcome read noise. https://www.cloudynights.com/topic/573886-sub-exposure-tables-for-asi-1600-and-maybe-qhy163/ John

Thanks. John

Thanks Ron. Very nice of you to say so. John

SW200p + ASI1600mm-Pro. Orion mini guide scope with ASI120mc. Around 20 x 200s and 20 x 260s each in Ha, OIII, SII. Lights, Darks, Flats and Dark Flats stacked in DSS, final image processed in PS. Still getting a few guiding issues in PHD2 where it says it's not optimum when the calibration has been done, but can't work out why. Hence, some of the stars are not as round as I'd like them to be. Scope is well balanced, with slight offset to reduce backlash and no cable snagging. I've got quite a few new things working on the way towards this image, so very happy from that standpoint: - Cartes Du Ceil controlling telescope. - Plate solving and syncing with telescope. - Drift alignment in PHD2. Comments for improvement welcome as always. Thanks John

Thanks, I'll have a look at that when I get some time. John

It looks very nice. I guess the downside is the additional cost. I'm doing everything from my terrace at the moment so using a laptop connected to the mains, hence there wouldn't be cost saving there for me.

Damn and I've just spent several days working out how to plate solve, sync and do everything else I need to in APT, PHD2 and Cartes Du Ceil. 😀

I'm running a similar setup (ASI1600mm-Pro and Orion Mini Guidescope with ASI120mc camera. I've found that it's vital (for me anyway) to run PHD2 as Administrator. If I don't, then some of the camera selection options don't appear in the drop-down boxes. Are you also running the ASCOM software? John

Thanks John

Thanks for the info. I'll definitely be using darks when I've got all the lights data. John

No, I haven't taken darks yet as I usually do these at the end when I have all the light subs I need. I've left the camera on the telescope so the orientation is the same when I come to take Ha, OIII and some more SII. I usually remove the camera to take darks so I can be sure there's no light getting in. I didn't know that it's vital to include the darks. I've seen previous posts where people say they don't use darks, but these may have been with different cameras. I'll have a go at the test you suggest when I've got the data. Thanks John

Thanks for the info. John

No, i didn't know I needed to do that, but I'll give it a go. Thanks John

Master flat and single sub uploaded. Thanks John MasterFlat_ISO0.tif L_SII_2019-06-27_23-14-01_Bin1x1_180s__-10C.fit

At least I know my problem isn't related to dew. 34 degrees C out here in Malta when I took the flats, so well above the dew-point. John

19x 180s SII frames stacked from last night's session. ASI1600mm-Pro @ -10 deg C. Flats produced using light panel over white pillowcase. I also tried an illuminated wall, but it turned out to be unevenly lit. Three different light levels were tried with the panel, but although the exposure times were different, the results were similar. Flats were also taken with the sensor at -10 deg C. Same SII filter was used. APT CCD Flats Aid was used to generate the image plan, with a target ADU of 20,000. Subs were stacked in DSS, then opened in PS and auto-contrast applied to enable a comparison. The first image was stacked without using the flats and the second image had 20x flats added. It appears the flats have added a dark area into the middle of the image. i.e. they've subtracted too much. Any thoughts on what I'm doing wrong? Thanks John P.S. My tracking wasn't good, so stars not great, but this obviously isn't relevant to the flats issue.

Ok thanks, that makes sense. I suspect I've already got it configured for my FOV as when I downloaded the index files, it gave me the option of only downloading those applicable to my camera/scope setup.

How do I restrict and prioritise the index files? I've had a look but can't see how to do it. Thanks John

Thanks all, some very helpful suggestions there, so I was able to look at a few things I hadn't thought of. I think I've finally got to the bottom of it after much daytime experimentation. I was aligning CdC exactly with Polaris to polar align the mount. Polaris of course, isn't in exactly the right position and I think this was confusing the software somehow. When it actually needs to look directly at Polaris, it has to slew the mount by about 6 hours in right-ascension at the time of the experimentation. I love this hobby 😀 Now I need to get plate solving working. John

I'm having some problems with this. I set up the scope to point to polaris, then set CdC to the same and in CdC do a right-click - Telescope - Sync Alp:UMi to sync to polaris. Then I try slewing to another object, but the scope doesn't go where expected. Also, sometimes it will give a 'below horizon' warning when it is clearly not. Any thoughts on what the problem might be? Thanks John

Awesome stuff Mike. Welcome aboard. John

Hi Tony. A warm welcome from Malta. It was more than 50 years ago that I first looked at the moon through a 2 inch department store refractor from the sunny skies of Birkenhead and wanted more. I hope you enjoy this fascinating hobby. John

Thanks all, for the help. Much appreciated. John

I've just got Cartes Du Ciel controlling my telescope, but of course the hand controller is no longer connected. So, my question is - how do I align the telescope now? The logical way I can think of is to make CdC point to Polaris, then point the scope at Polaris. Then slew to another object and adjust scope as necessary for a sort of 1 star alignment. Is this correct or am i barking up the wrong tree? Is there a better way? Thanks John