Forum Replies Created
-
Posts
-
These are good observations from our European friends. British observers were on chords near position (3) on the DAMIT shape model (see Link from Alex) where the duration was about 25 seconds. This area of the profile was sparsely covered as a result of obscuration by cloud.
I was clouded out and this is the same story for many. However there are a few lucky observers in Europe who got a clear view of the occultation. Thanks to all who peeped outside. There are few opportunities to see (2) Pallas occult a star of sufficient brightness. This was one of them.
There are many asteroids and many stars, and the best place to look for predictions for favourable event is Steve Preston’s pages: https://www.asteroidoccultation.com/
The Asteroids and Remote Planets Section will be pleased to receive your observations.
Tim
Great video – thanks for the link Alex,
For those who may inquire, why telescopes shine lights into the sky? Well from what i understand this is part of the adaptive optics feed-back system. It doesn’t effect the images. A wiki would be the best place to seek further info on this.
TimGrant: Yes, time dependent events like this are particularly prone to weather conditions. There are 25 observers across Europe, 7 in the UK that i know off. Best of luck to them all. A number of chords across the asteroid will help refine its shape. We have no direct imaging, and based on light curves its not spherical.
To update you Alex, i connected my QHY174m-GPS camera to a 50mm F/3.6 finder. This was from Orion Optics originally but suspect it is a standard design. The instrument was in the polar home position. I adjusted the three finder alignment screws to bring the pole star a bit nearer the center using an eyepiece, then plugged in the camera. The scope had been parked from the previous nights observing. I focused the camera and the pole star was at the edge of the CMOS field. Its not necessary to have the pole star detected though.
I went through the routine with ShapCap Pro which is well explained with on-screen popups. The offset was measured from the automatic plate solving as 7′ arc. This was from a drift alignment originally but i knew it was a bit off. Polar alignment plate solve is build into the routine. Then i moved the scope 90 degress in RA as requested by Sharpcap.
After making corrections to the alt/az screws the routine reported 1′ arc. I could have got a bit closer but reckoned I was at the limit of the adjustment screws on the mount. So i settled with this. Now the guiding is very good indeed and gotos are spot on.
Cheers..
Hi Alex,
Thank you for your reply. My solution was to set up a similar arrangement with the dew band around the C11 OTA, and a Celestron dew shield over the top. The Celestron dew shield is quite heavy, so your foam mat is a better idea. Im now using my Newtonian in a Pulsar 2.7m so dew is much less of a problem.Cheers –
I wasn’t aware there was an earthlier design. The 2.2m Pulsar dome is advertised to have the dome drive – apologies for the miss information.
I agree with Jeremy. I had considered exactly the same proposed setup as yourself, but concluded i wouldn’t fit in the dome with the scope 😉 However i suggest that a motorised dome rotation would overcome the narrow slit difficultly. It works very well on my 2.7m Pulsar. I align the aperture on the OTA, and select sidereal rate on the control box. The azimuth drive system can be retro fitted.
I also find the variable bright at r 12.88 +/-0.05 (Unfiltered CCD, GaiaDR2/Astrometrica). Poor conditions of drifting high cloud in Moonlight Measurement were from start, mid and end of a frame sequence at 5s intervals for 20min.
A web-cam on the finder is a useful arrangement. Since i already have a 9×50 finder and a suitable camera, i bought one of these from FLO: https://www.firstlightoptics.com/adapters/astro-essentials-sky-watcher-9×50-finder-to-t-adapter.html.
Agreed, Its helpfull to have some form of dark frame subtraction to remove hot-pixels if the web-cam is used with longer exposure settings. False stars can be confused with real ones !Thanks Dominic, I will contact Novatech who made the laptop which is W7 i3, 4GB and SSD. I have now overcome the initial memory problem.
When I installed the 64bit version of Anaconda3 (2020-11) and HOPS 3.0.1, and use by own FITS files from a QHY174 – which are 4506 K each – HOPS progresses all the way to a preliminary light curve. The program analysed 1300 FITS files in about 30min, with 65% memory usage and 20% processor power.
The computer falls over when trying to process 32000 K FITS files often used in a Tutorial. So although the the HOPS 3 Manual says 4GB RAM or more – the relevant word is “More”. I would say my camera was typical mid-sized 12/16 bit CMOS, and these smaller files are handled OK with the old computer, and ageing operator !
Alan
With the WAT910HX / RC you have the makings of sensitive asteroid occultation timing setup. The addition of a GPS video time inserter, a larger aperture lens and a controllable mount is all that is required in terms of hardware to make useful observations. A clear sky would be nice too, but we can hope.Tim
Thank you Philip and Alan for your observations. The movement of the path is typical of predictions for higher numbered asteroids. Sometimes this can favour an observing location.
There have been a number of MISS reports (no occultation) from observers in SE UK and Europe. Observers who happened to be in or close to the predicted shadow were clouded out this time, and no observation made. Two observes in England detected small drops in the light curve, and these were attributed to cloud passing, since the time of these obscurations were outside the expected occultation window.
Thank you to all observers, and i expect there will be more bright star events in the future.
The Asteroids and Remote Planet Section (ARPS) has a group of observers making regular recordings of fainter star predictions. ( Magnitudes in the range 10-14 ). More than 50 stellar occultations were reported (positive) last year.
I would also check in Device Manager, the status of the USB controllers. There should be no errors shown
TimIm not an expert – and sorry ive just seen your request. In the section on Universal Time, GMT starting at Noon was also referred to as GMAT, Greenwich Mean Astronomical Time – a very minor point.
I like the new facilities very much, but has the zoom in (enlarge) link been removed ? (Sorry if this have already been discussed)
I have had success with F/4 Newtonians on a good GOTO mount. At the other end of the scale a short focal length lens on a portable tracking mount should give pleasing results when images are stacked. I use 50 to 200mm prime lenses but ive had good results with 18-105mm zoom range. If you are interested in timelapse, then it would be possible to put long exposure wide angle frames into a movie that includes foreground objects.
