Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_celestial_motion.thumb.jpg.a9e9349c45f96ed7928eb32f1baf76ed.jpg

frugal

Members
  • Content Count

    812
  • Joined

  • Last visited

Everything posted by frugal

  1. Unfortunately my mounting technique caused some problems. It made the scope far too camera heavy, and the mounting box also clipped the altitude adjustment bolt. So I have had to take it off again until I can come up with a new mounting approach
  2. I probably wasn't clear, by "the roller" I meant the bar that runs from one focus wheel to the other. My ED80 focuser works by having the metal bar that the focus wheels are connected to rub against the focus tube. The whole reason that the focuser seems to work is because there is friction between the metal bar and the metal draw tube. Obviously you don't want PTFE to make this bit slippery
  3. What does the PTFE rub against? Is it the metal draw tube? I presume that the roller connected to the focus wheel does not touch the PTFE?
  4. Alas, I did not manage to capture any meteors on camera, but the image did come out to be a fairly good wide field shot of the sky. MY field of view calculations must have been out, as I have got a lot more sky in the frame than I expected. I was anticipating only just getting Vega and the square of Hercules in frame, but I have managed a lot more to the right of Hercules as well. As I was shooting across town there were some horrible gradients that I could not get rid of even after spending about an hour with PixInsights back ground extraction tools. You can also just about make out Comet P41-Tuttle between Hercules and Draco.
  5. I have not worked up the courage to tear apart £1,400 worth of mount yet. I have read the stripdown document and it scares me somewhat. I am the sort of person who always ends up with a couple of screws left over after that kind of operation.
  6. So if I nudge the scope a little West before I start the calibration and the problem goes away then it is probably backlash. If I still have the problem then it is more likely to be balance or binding?
  7. I made that I was on the West side of the Meridian, so I had 11 and a half hours to get the calibration sorted? The PHD docs just state that the discrepancy between RA and Dec rates indicates a problem, but gives no clues as to what kind of problem it might be. The Dec rate at 7.4 is pretty close to the rate it should be for 0.5 guide rate, so I am assuming that the problem lies in RA.
  8. It is a clear night at last. I do have to go to work in the morning, but I have a couple of hours to try to crack this PHD issue. So I point at the Southern sky just by the Celestial equator: I run the Calibration on this star and I get a fun new error that I have not had before: hmmmm.... I am currently running the guiding assistant to see if that helps.
  9. What do you have your horizontal axis set to in PHD when you do this? I generally use 100 readiness and 2 second exposures. I generally let it do at least 50 of them before I adjust (so 100 seconds)
  10. I thought that Bleeding Edge was fairly common parlance. Cutting Edge is the latest greatest thing; Bleeding Edge is the next Cutting Edge, but still under development so you often get cut.
  11. I was imaging the Lyrids from 11pm to 3am when they went over the house (when the polar-scope batteries on the Astrotrac died, so my attempts at re-positioning the tripod failed). I saw a couple of short small meteors, but none of them made it to the images based on my quick look. I will go over them in more detail and hope for something faint. Lovely images of the star filled sky when I quickly stacked them in PixInsight, so it was not a complete loss. It was dark enough to faintly see the milky way at about 3am as it rose through the murk of the atmosphere. I tried to polar align by eye without the polarscope and image Cygnus, but I was so far out that there was horrible field rotation.
  12. Looks like the cloud might not be as bad as I thought. Astrotrac set up and taking 2 minute exposures. Changed the framing at the last minute. It is too early to put the radiant at the top right of the frame, the rest of the image would be down in the murk of the atmosphere. So I have gone for the radiant and Vega in the. Bottom left and the square of Hercules in the top right. Herself already saw one meteor as I was setting up, but nothing on camera yet.
  13. It looks like all of the cloud that was supposed to be overhead all day has decided to wait until nightfall to arrive... grrrr... no clear spots predicted until 7am...
  14. You are not filling me with confidence here Dave...
  15. Unfortunately not. My choice of lenses are the kit 18-135 f3.5-5, or the 28mm f1.8. As I am using a crop sensor the kit lens is more like 29-216mm and the 28mm lens is more like 45mm (perfect for framing a single constellation which is what I got it for). The one consistent piece of information in a lot of the tutorials is that anything slower than about f3 is unlikely to catch many meteors, which is the main reason I am going to use the 28mm.
  16. Ok, so tonight is the peak of the Lyrids, there is little moon and there is finally a forecast for a few hours of clear sky. So I figured I would take the Astrotrac out to a darkish location and try to get some images (I figured AstroTrac rather than plain tripod as I will get less star trails). My weapon of choice will be my trusty Canon 60D (unmodified) and the lens will be a 28mm f1.8 (I could use the kit lens 18-135 F3.5 to get a bigger field of view, but a lot less light). So my question is, how should I frame a metor shot to get a decent selection of trails over the night? I could put the Lyrids slap bang in the middle of the frame, but I am lead to believe that I will not see many meteors as they are not very visible close to the radiant. So would I be better off putting the Lyrids off to one side like this, where I am covering about 90 degrees around the radiant: Or putting the radiant completely out of view, and hoping that enough metors cross the frame to make something interesting, like this: My concern with the latter approach is that I am only covering something like a 45 degree section of the sky around the radiant, and as there are only 18/hour expected, I am only going to get at most 2-3 in frame per hour, but hopefully they should be longer and brighter further away from the radiant. Any advice from experienced meteor hunters? I have looked and looked online, but all of the tutorials essentially boil down to: "take your £5000 full frame camera and your £1000 10mm F1.2 lens out to somewhere darker than satan's armpit where you can cover the whole sky"
  17. What was it about the bat wing design that caused dew to form?
  18. That would also work. In all seriousness there are a couple of places you can put your images to share: - Instagram - Flickr.com - They have an Astrometry group and if you add your images to the group they are plate solved and annontated by Astrometry.net (takes a couple of days) - Astrobin.com - Where I initially put my images up. You can add details of the number of light and dark frames, and it will calculate the total integration time as well as plate solve and annotate the images; you can also have multiple versions of the same image if you canture more data or improve the processing. However it go so popular that the site maintainer needed to move to a paid model in order to keep up with the bills. Currently $18/year for 12 images a year, or $36 for unlimited. - dso-browser.com - I had not really appreciated the image abilities of this site, but like Astrobin you can upload an image along with all of the details of the equipment used and the number of integration frames; automatic plate solving. It also adds your image to the community images for a target, so that if you look at the details of a target you get to see everyones images. The only thing you can not do is upload a revised image if you improve the processing. The only problem is that there is no easy way to share the images to the forums (sharing to Facebook, Twitter and Google+ is fully supported).
  19. I believe you are only allowed to post astro images on Instagram if you first apply a faux 1970's Polaroid filter, or show it next to a plate of food ?
  20. I call myself Frugal because I can't spell Parsimonious Just to let you know, that "Page 6" is just the HFR code, and it assumes that the centre of the image is set up to be the centroid of the star. The next page "Page 7" has a full star detection algorithm and HFM analysis of a full image. I did have a look at Astropy to see if they had any kind of HFR or centroid detection, but I can not find anything. It is great for loading FITS files if you have not yet discovered it.
  21. I would be concerned that the contrast when you are at a star edge would be swamped by the noise that makes up 95% of the image that is not stars. Half Flux Radius seems to be the current favourite (it is declared to be an improvement on FWHM). A C implementation of it is here: https://www.lost-infinity.com/night-sky-image-processing-part-6-measuring-the-half-flux-diameter-hfd-of-a-star-a-simple-c-implementation/ It should be relatively easy to convert the C to Python.
  22. I have double checked the centering of the polar scope against a distant object during the day. It is nicely centered. I am hoping that this evening might actually be clear enough to get the scope out and re-test everything
  23. I have an 8Tb NAS box that I keep a backup of all of the CR2/FITS files on. My general process is to capture on the cheap toughbook, and then at the end of the session, I copy all of the files to the NAS box, one folder per day. Each file has the target name in the title as well as the date (.../2017-04-08/M101_Light_ISO800_300sec_f0012_2017-04-08.FIT). So when I want to process something, I can search for and copy all of the "M101" files onto the PC to process. I also keep a Flats directory for each day.
  24. Halon was banned years ago. The current equivalent is FM200, but that is only really used in data centres where you can dump it into a sealed room. Plus you generally need to evacuate the room before you dump it as it works by consuming all of the oxygen before the fire can. For observatory equipment in a shed you are looking at Class A (Wood) and Class E (Electrical). Unfortunately there is not one extinguisher that deals well with both. You really want a Foam extinguisher for the wood (Water is out because of the electricals, and Powder is out because it will get everywhere and likely ruin all of your telescopes / electricals) and a CO2 extinguisher for the electricals.
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.