petevasey

I was fortunate with sky conditions last night here in Northumberland, and managed to image the eclipse right through to the exit from the Umbra. Unfortunately although the sky was decently clear for totality it hazed over as time progressed. Nevertheless I was able to capture a good selection of images. So here is a composite of before and after with the images in correct configuration and spacing to show the shape of the Umbra. And of course a separate image of totality. Canon 700 D on Meade 127 refractor (950 mm fl).. The exposure hour times and settings were: Before 0403 1/200th second Totality 0511 10 seconds After 0625 1/50th second (haze necessitated a longer exposure) All at ISO100 Cheers, Peter

I've now produced an animation of 16 frames showing the movement over 90 minutes. There is a slight jump, a couple of the originals were unusable. Small version below, a larger version is too big at 2.68 MB for the size limit, but can be found here. As you can see by tracing the path back, the coma would have passed over the galaxy. A pity there was a bright Moon - if it had been New, with full darkness at 6.30 pm on 16th instead of 4 am on 17th, the comet would have been at its closest to the galaxy at the start of the imaging run and I would have many more exposures and a much longer animation. Peter

Last night (17th Jan) the comet was due to pass very close to the interesting 11th magnitude Polar Ring galaxy Arp 336 (NGC 2685) in Ursa Major. I kept my fingers crossed for a clear sky in the small hours (Moonset was not until 4 am) and for once the sky gods smiled on me and after a snowy cold front passed through it was beautifully clear for a couple of hours. I used my Canon 700D on my 10" RC scope (2000mm fl) to try for some galaxy detail with a succession of 5 minute subs - any longer would show too much movement of the comet at that focal length. Guided with a Lodestar on a Celestron off-axis guider. And this was the result. The galaxy really needed much longer exposures, but the polar ring is just visible. The two distant edge on galaxies in the lower part of the image are (reading down) PGC 25034 (mag 17.1) and PGC 25046 (mag 16.7). 16 x 5 minute subs, darks, flats and bias frames also used. I already had an image of Arp336 from 2008 and there was enough detail and nearby stars to position it exactly in the second image. But I realise that because the galaxy image was captured some years ago, that version cannot be submitted to the competition - I just include it out of interest. Cheers, Peter.

The Igloo looks interesting, but that's a heck of a price for a fabric Observatory! And I don't know if it would be suitable for the UK climate. Regarding condensation, any Observatory because it must essentially be unheated can be prone to condensation. I have a small dehumidifier in mine which keeps it nicely dry. The only time I don't run it is when it's windy - that causes a small flow of air via the dome overlap, so the dehumidifier would be drying the environment, and the airflow minimises condensation anyway. Yes, there's a price to pay for it and the electricity to run it, but when you consider there is £1000s worth of kit in there, it's well worth it. One thing I particularly like about the Astro Booth is the full height door! I long ago lost count of the number of times I have banged my head going in and out of my Obsy, even though the door is fairly high on mine at 4'4" (132 cm). I would suggest you get some cheap hard wearing carpet for the floor - easy to vacuum, warmer and more comfortable for the feet and easy as pie to fit - just lay the flooring panels on top of the carpet and cut it out before fitting the panels to the frame! See here. Cheers, Peter.

Hi, Paul, Presumably you favour a roll-off-roof design rather than a conventional dome. And this one looks to be very cleverly designed and robust. But might be worth mentioning that the Pulsar 7' dome is almost the same price. Certain advantages to a dome - better protection from the wind and local light pollution, and a lower horizon. By that I mean that with a ROR unless you have drop sides you need to mount the scope as high as possible, and if a GEM, park it to one side of the pier rather than in the usual polar position. On the other hand you can only see a small part of the sky through a dome slot, and unless you motorise will have to keep nudging the dome round quite frequently. But a variation on my own dome drive with pinch rollers on the Pulsar inner rim would be a low cost solution - I can get 3 or 4 hours unattended even with my 10" scope. Maybe I'll get round to fully slaving to the 'scope, but generally it meets my needs admirably as is. Cheers, Peter

Last night (13th Jan) started off with broken cloud and moonlight. I needed to try an experimental setup, so occasional clouds didn't matter. But as midnight approached and the Moon lowered in the West, the sky cleared beautifully! As usual it wasn't forecast, but I had the old open cluster M67 (in Cancer) on my repeat list, and as it was well placed and would just fit I reverted to my normal setup and went for it - too late for the longer exposure time required for a 'faint fuzzy'. Clouded over fully around 0300 but I had enough data by then. Luminance 7 x 5 minutes, RGB each 5 x 5 minutes, all unbinned with QSI683 and SX AO unit on RC10 Truss. Cheers, Peter

True. But the pixel values in the RAW frame will depend on the levels of Red, Green and Blue light passing through the Bayer matrix to the pixels behind the filters. The colour information lies within those pixels and the debayered colour will depend upon the pixel values of each group of four. Therefore when they are subtracted from the image files, the final blue balance will be incorrect unless the flat is neutral. When I take flats for my monochrome CCD which of course uses external colour filters so I have to take a flat for each filter, I endeavour to have similar average values for each flat to counteract any colour bias from my light source. It would appear that the light box being used in this thread has a blue bias, which will then affect the final calibrated image. Peter

I never said anything about debayering. I've never had to manually debayer RAW (CR2) files from my Canon - DSS does this within the program, presumably bias, dark and flat calibrating the target images first then debayering them before stacking. When viewed within Canon's Digital Photo Professional program the images are already debayered on screen. If I'm not using DSS, I convert all the RAW files to TIFFs in DPP before further processing. But if there is excessive blue within the RAW flat, that will also weaken the blue within the image. Maybe I didn't make myself clear earlier - when I said 'blue flat' I was referring to the original coloured flat shown at the beginning of this thread which had a strong blue bias - look at the histogram. To me the later balanced version is much more suitable. Peter

Not in this case tho' because a one shot colour DSLR is being used. Therefore a blue flat will weaken the blue in the image. That can of course be corrected in further processing, but surely better to have a neutral flat to begin with? Glad to have been of assistance, Olly Cheers, Peter

I have a TS65Quad which does an excellent job. It's 420 mm focal length and f6.5 so a lot 'slower' than your lens even stopped to f4 . Useful that the flattener is built in, - just fit and focus the camera. Beautiful crisp visually as well. They now do slightly larger models, but all slower than your lens, and the fastest one is pretty pricey. I've mainly used mine with my QSI683, but here is an image of Comet C/2014 Q2 Lovejoy from March 2015 with my (modded) Canon 350D which of course has an APS size sensor. As you can see the stars are good right into the corners. (The cluster is of course NGC457). I also have a Canon EF 400 f5.6L lens which also gives excellent results, but can't be used with an off-axis guider. This is another shot of the comet, this time with my Canon 700D, and the 400L lens fully open. Not much to choose between the images, the lens is a lot lighter than the telescope, but nowhere near as versatile for astro work. And cost a fair bit more than the quad. Cheers, Peter

Going back to the size problems, I've had a look at a couple of my images from a 350D and 700D In both cases jpeg images show the correct size in DSS version 4.1.1 (as also shown in Photoshop and Canon's Digital Photo Professional) But the RAW (CR2) files show incorrect sizes in DSS although correct in DPP. For the 350D as 3474 x 2314 instead of 3456 x 2304. And for the 700D as 5208 x 3476 instead of 5184 x 3456. Strangely when I convert the CR2 to TIFF within DPP the size remains the same at 5184 x 356. BUT when I convert it using Pixillion Image Converter the TIFF and jpeg sizes are then 5208 x 3476 !!???!! Cheers, Peter

Looks promising albeit rather on the blue side, no doubt due to the LED's used in the panel. Maybe once you have stacked your master flat, it would be worth adjusting the colour to give a more neutral tint. If you have Photoshop the 'WhiteCal' function of the free plugin Deep Sky Colors could help. (The other plugins there are useful, particularly Hasta la Vista Green!) I made my own light boards some years ago using electroluminescent panel material. They do a good job, but your solution is much cheaper and probably good for telescopes up to 8" diameter. Hugely cheaper than commercial telescope light panels for example these where an 8" panel costs €155. Also very handy that it runs off USB Power from your computer - no separate external power supply needed. Cheers, Peter PS While I was writing this, you added the histogram information. So if you can adjust the master using that, then that will be ok.

In normal tracking on a Gem like the EQ3, the DEC motor does not run while tracking, only if there are guide camera corrections. But you say you ' slew it to a target '. Does that mean that the GOTO is working correctly? I presume it's this mount. Do both motors respond to manual controls? If not, about all you can do without delving inside and looking for blown fuses or burnt components is check the motor cables - unplug and replug several times to self clean the connections. If that fails, it might be worth reflashing the firmware in the handset - it could have become corrupted. Another thing you might try is opening up the handset and cleaning the contacts for the buttons. Use a pencil eraser. But I'm not sure of the construction - my handset (EQ6) is not available at the moment. Best of luck, Peter

That's unfortunate. Frustrating and rather strange. Who knows what goes through the mind of Canon designers Cheers, Peter

Triangular stars are usually an indication of 'pinched optics', possibly due to over tightened primary mirror clamps. See this link. But it may be just that your scope needs collimating. If you don't know how to do that, these articles might help: Gary Seronik Sky and Telescope AstroBaby Best of luck, Peter