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About Ikonnikov

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    Star Forming

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    West Yorkshire
  1. I'm guessing the signal to noise for the short exposures required in this study wouldn't be high enough using a smaller aperture system (with much lower limiting magnitude). Camera lenses have been used in other professional setups I've seen e.g. http://mascara.strw.leidenuniv.nl/technical/ and https://www.canonwatch.com/canon-ef-400mm-f2-8l-ii-lenses-used-discover-new-dark-galaxy-dragonfly-telephoto-array/ although in the latter one, each lens costs the same as 3x 11" RASA scopes!
  2. An interesting study published in Nature Astronomy using amateur off the shelf gear for some occultation photometry (alas full article requires online purchase or journal subscription but abstract, figures and raw fits data available here https://www.nature.com/articles/s41550-018-0685-8). In essence they’ve done a lot of high-speed photometry using two identical setups situated on opposite sides of a building roof in Okinawa (both observing the same region of sky) and looked for occultations of any stars with the appropriate decrease in magnitude for the appropriate duration (up to around 1 second for ~1km diameter object) recorded simultaneously with both scopes (to rule out non-astronomical interference like birds/bats etc). To record such a fast transit with enough (temporal) resolution they had to use very short exposures (~65ms) which requires a very fast optical system to gather sufficient light. To achieve this, they used a Celestron Rowe Ackerman 11” scope (already F2.2) and made it even faster with a DSLR to M43 Speed Booster (Metabones 0.71x) and acquired images with a ZWO ASI1600 CMOS camera. Crazily they can get a usable signal for stars down to magnitude 13 with these very short exposures. Unfortunately for the budding amateur scientist, what is described in the paper as an ‘extremely low cost’ system still comes to $16,000 per setup, but nonetheless it’s interesting to see what can be done with gear that people do own here on SGL (albeit not usually in duplicate!).
  3. Thanks for your reply Peter. Yes, on balance I think a small roll off is probably the best option for me all things considered. The functionality of a dome is attractive and the price of the basic small pulsar within reach, but I think the added cost to allow full automation and the appearance in my smallish garden make a ROR option my preferred choice. Paul
  4. Hi Folks, I've been thinking for a while about trying to increase my imaging time by either using remote scope hosting or getting my own observatory and am leaning towards the latter currently (if only I had the dosh to do both...). I currently image from a concrete-mounted metal pier in the corner of my back garden (mount/pier covered with a Telegizomo 365 when not in use) so was thinking of putting a simple small obsy over this (no requirements for warm room or doing visual from it). I don't have the time or skill level required to build my own (certainly to the quality I would be happy with!) so I'm looking at commercial options. After some internet searching I came across the 'Astro Booth' http://astrograph.net/epages/www_astrograph_net.sf/en_GB/?ObjectPath=/Shops/www_astrograph_net/Products/AGOABOOTH which seems to meet all my requirements and be reasonably good value compared with similar alternatives, being fairly compact/robust, relatively easy to construct myself (and dismantle if I have to move house) and with a motorised roof and delivery included in the price. I've only come across one account (at least in English) of someone buying one and they seem to like it, although they used it in Spain so might take a bit more of a battering/soaking here in Yorkshire. Would be grateful if anyone else has encountered one or has any thoughts/opinions on it (good or bad) from the website material etc. Cheers Paul
  5. Very nice Barry. This remote imaging thing is looking increasingly tempting!
  6. When I bought the RC second hand it came with this corrector https://www.teleskop-express.de/shop/product_info.php/info/p2646_TS-Optics-PHOTOLINE-Full-Frame-APO-Corrector---Flattener-for-astrophotography.html (if I remember correctly) which is supposed to be very good for RC from reading around and looks the same as the one you're referring to. Unfortunately with my modified backplate/replacement TS focuser I didn't have enough in-focus when using it at the correct spacing distance. Instead I have this now https://www.teleskop-express.de/shop/product_info.php/info/p4006_TS-Optics-2--corrector-for-GSO-Ritchey-Chr-tiens-w-o-focal-reduction.html (and also this https://www.teleskop-express.de/shop/product_info.php/info/p5120_Riccardi-0-75x-APO-Reducer-and-Flattener-with-M63x1-Thread.html which I'm currently trying out with an Apo refractor), both are small enough to insert inside the 3" focuser drawtube so I can achieve focus ok with them, also they're big enough to avoid significant vignetting on the 16200 chip. Obviously this applies to my 10" RC so things might be different for a 12". Definitely handy if you can fit your corrector in the focuser though.
  7. You can utilise the NIR preflash feature (followed by some CCD clear cycles) as indicated in the image on the Moravian instruments website for the G4-9000 camera, but the default for the G3-16200 is to have 0 sec for NIR preflash (i.e. no preflash) but 2 for Num clear (i.e. 2x clear cycles) so I assume the clear function is important regardless of whether or not you do the preflashing. The KAF9000 chip is very prone to RBI so the preflash is almost a must for this camera but the KAF16200 (and closely related 8300) show virtually no RBI signal down to at least -25C in my and others' (e.g. see Cloudy Nights forum posts) experiences.
  8. Here's an integration and simple stretch of a dozen or so lum frames from the same imaging session (where I managed to guide keeping the target in the centre of the frame). You can see the off axis aberrations in the corners which the field flattener should take care of.
  9. Thanks Richard, no I haven't got round to sorting out the secondary recoating yet, been distracted by various things including deadlines for work and another telescope purchase of the refracting variety (on which I'll post something eventually...).
  10. Thanks Dave. There's a fair bit of distortion in the corners with this set up but overall the uncorrected field is surprisingly good. These images are substantially cropped but not entirely central crops due to position of appropriate guide stars in the field. I'll try to remember to post an uncropped lum sub later. The quality of the stars across the same sized chip should be better in the 12 inch version. I have a 2"TS rc flattener but not bothered to use it yet as i needed to get collimation sorted without it (and also is a hassle to fine tune the spacing). I also now have the small riccardi reducer/flattener to try which gives a slightly less oversampled 0.75 arcsec per pixel along with correspondingly larger fov.
  11. Thanks for your comments guys, a mixture of opinions on which version looks better. I've run the scnr green a few times during processing but I think the PCC has pushed it to a browner tinge. Also a few more blue subs went into the second image so blue signal probably a bit stronger there to start with.
  12. I've been messing around on and off for a couple of years with an Altair Astro RC10 I bought from UK-ABS (replacing the focuser and backplate, remounting the primary in the cell and playing around with the collimation) but this is my first post of any images from the scope despite the files sitting on my hard drive for ages. The first image contains only data from the RC10 (without a flattener) and a G3-16200 CCD (5h lum and Ha 1x1, 3h RGB 2x2, ) and was colour calibrated using the Pixinsight Photometric Colour Calibration module. The second contains the same RC10 lum data but RGB and Ha data is a mix of some from the RC10 and the rest from my old C8 (using an Optec 0.5x reducer and atik 490EX CCD) totaling slightly more data overall albeit at a lower resolution. Colour was calibrated for the second image using the standard Pixinsight CC module. Although there's too much saturation (and slightly less fine detail) in the second image I think I prefer the colours even if the first image is supposedly more accurate. Grateful for any opinions/comments, Paul
  13. In short I have had no issues with calibration when bias, flats (and darks) were taken using SIPS, regardless of which capture software i use for lights. I only started having problems when I captured some new calibration frames in SGPro and noted that there was some inconsistencies in levels but can't remember the details. The end result was over correction with flats and inverse dust bunnies when trying to calibrate my light frames. I put this diwn to the fact that SIPS includes 2 ccd clear operations between frames by default (i assume this is a function to remove any residual charge after the image dowload without having to do a proper readout but am not certain) but SGPro doesn't. It could be something else entirely but as i say everything is fine if I stick to SIPS for acquiring my calibration frames. Hope this helps Paul
  14. Hi Dave, I have had the Moravian G3-16200 (original version) for a few years now and have never had any noticeable problems with RBI using it at -20C or -25C. My G3 does have the RBI NIR pre-flash feature but I have never had the need to use it (even shooting flats); I would assume that the updated version also has it but I guess there is a chance they could have removed it. What I have noticed is that for consistent calibration the camera needs two CCD clear cycles between exposures (as is set by default in the Moravian SIPS capture software) or the background levels can start to drift and flats don't work properly. Paul
  15. For fine tuning collimation under the stars with imaging camera attached the procedure below works beautifully. You need to start with the collimation reasonably accurate though, e.g. set using a cheshire, collimating telescope etc. https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.deepskyinstruments.com/truerc/docs/DSI_Collimation_Procedure_Ver_1.0.pdf&ved=2ahUKEwjou_G9h43eAhXlJcAKHdUvDtoQFjAAegQIAhAB&usg=AOvVaw1TQ8YAhohC9_gr_IRXBo3x
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