I was hoping that the tightly spaced Jupiter/Mars pair would clear the trees before the dawn sky brightened too much – the trees blocking my Eastern Horizon had grown considerably in the last 12 months.
Tantalising glimpses of Jupiter and the 4 Galilean Moons materialised on the LCD on the back of the camera as the topmost branches swayed in the light breeze when finally, Jupiter and Mars cleared the top of the trees and I could get to work recording this close conjunction.
I took several frames at varying ISO speeds (ISO100 to ISO3200) and shutter speeds (1/8 sec to 30 secs) so I could later select frames that showed the field stars (Jupiter and Mars grossly over exposed) and the disc of Jupiter with the equatorial bands.
A little bit of Photoshop magic allowed me to combine the sets and produce this composite.
Cheers
Dennis
PS - According to ST3 Pro, the separation between Jupiter and Mars was some 14 arc mins, less than ½ diameter of the full Moon. Brisbane, Qld, Australia, 7th Jan 2018 at 4:15 am AEST (UT+10).
Doing minor planet astrometric work, I will often use SkyTools3 to generate an observing list of minor planets (alongside of the Minor Planet Centers list generator). I concentrate mainly on NEO's and use the database search tool to put my list together, I am able to single out what particular type asteroids are, Aten's, Apollo's etc. However when I generate my list, the only ID shown of the minor planets selected is the name and or number ID. Is there a way to also list what type of asteroid it is? For example, I print out a list of asteroids visible for the night. While I could see what type of each was in the database search, once I create the list and print it, I only have names and numbers, nothing to tell me the types. It would be great if the types were also listed. Maybe I am overlooking something.
Looking forward to Nereid being included in ST4 - thanks Greg.
In the meantime, here are a couple of images of Nereid taken from my back yard on 27th & 28th August 2016.
Taken using a Tak Mewlon 210, Tak x0.8 Reducer/Flattener and an ATIK 414 EX camera. I captured 75x60 sec frames on 27th Aug and 37x120 secs on 28th Aug. Images were calibrated, aligned and stacked using CCDStack2 and finished in CS6. You can easily see the movement of Neptune, Triton and Nereid against the field stars over the two nights of 27th & 28th August 2016.
The full size originals have a FOV of 15.2 x 11.3 arcmin at 0.65 arcsec/pixel. The 1024x768 crops have a FOV of 13 x 9.7 arcmin.
I would have thought that there would be a lot of posts here. After all, observing double stars is the most fun you can have in Astronomy!
I do have a real question. I love how SkyTools has made my double star observing a snap. This has probably been answered before, but are there improvements specifically for doubles in ST 4?
On the Minor Planet Mailing List today (19-Nov-2017), Alan Hale, of Comet Hale-Bopp fame, posted this alert...
Quote:Just to remind everyone, Phaethon passes 0.069 AU from Earth on December 16 [2017] — the closest it has approached Earth since its discovery in 1983, and it won’t make a closer approach until 2093. Right now it’s moving rather slowly – barely over 10 arcminutes per day — since it’s coming almost right at us; when closest to Earth it will be traveling at 15 degrees per day and should be as bright as 10th magnitude.
Will this be close enough to require special elements in ST3? Since 0.069 au is about 6.4 million miles (10.3 million km), I'm guessing it won't, but I'm not the expert on this.
BTW, 15 degrees per day is about 37.5 arc seconds per minute of time, or roughly a Jupiter diameter per minute. I then checked it in ST3, and for December 16 at 6:45 pm EST (when it transits for my location), the total motion is given as 38.6"/min.
More with hope than confidence, I set up on Sunday night, 15th May 2016 to see if I could record the two moons of Mars; Phobos and Deimos. I expected Deimos to be fairly straightforward, lying some 60 arc secs from Mars but Phobos would only be 24 arc sec distant, bathed in the glare of the Martian disc. The seeing was very good and when the results came in, Deimos was unmistakable and I had a few grains of light as a promising candidate for Phobos. After much image processing and stretching of the data, I was able to get everything to “pop out” in one aligned/stacked frame, including 4 field stars. Taken with a Tak Mewlon 180 F12, TeleVue x2 PowerMate, Atik 414EX CCD camera, 20x4 sec exposures, 10:08pm AEST. For the disc of Mars, I used a ZWO ASI224MC CMOS camera and overlaid the (re-sized) image over the grossly over-exposed Martian disc. As usual ST3 provided the confirmation when I overlaid an ST3 screen capture and the plotted positions in ST3 precisely fitted the imaged positions. Cheers Dennis
On 24th October 2017 I managed to record the 5 brighter satellites of Uranus; Ariel, Miranda, Oberon, Titania and Umbriel. SkyTools 3 Pro was used to confirm the positions of 4 of these, namely Ariel, Oberon, Titania and Umbriel. The following (edited) data was Copy/Pasted from ST3.
Uranus details: Magnitude: 5.69 Size: 3.7" Earth Distance: 18.9 AU Diameter: 51118.0 km
Satellite details: (Name/Mag/Angular separation) Ariel 14m3 11.2” Miranda 16m7 09.5” Oberon 14m1 41.9” Titania 13m9 23.4” Umbriel 15m0 14.5” Equipment details: Takahashi Mewlon 210 F11.5. TeleVue 2” Powermate x2.0 Efl 4830mm at F23 Camera details: Atik 414EX Camera Exposure 30sec 5 frames Image scale of 0.28 arcsec/pixel It was a tough job digging 16.7 magnitude Miranda out of the glare of the disc of Uranus but choosing the time of maximum elongation (9.5 arc secs) and favourable seeing, made the task feasible. SkyTools has consistently plotted these fainter objects reliably and accurately compared to the other two Windows PC Planetarium programs that I also use. When chasing some of the more rare objects, it is comforting to know that I can rely on the accuracy of the SkyTools data. The ST3 overlay in the 1st image shows how accurate ST3 plotted the 4 brighter satellites of Uranus. Hey Greg – will Miranda be added in ST4? Thanks Greg, for such a fantastic, feature-rich program. Cheers Dennis
So this is likely one of the worst images of a comet you are going to see. But that was sort of the point. This is a Track & Stack in Astrometrica of three 4-min exposures from last night. The remote imaging system used was T21, located just a few miles down the road in Mayhill, NM, via iTelescope.com. It is a Planewave 17" CDK with an FLI-PL6303E camera.
As with most of my imaging these days, this was a SkyTools 4 test. A little backstory first: stellar and diffuse objects are modeled differently. A diffuse object, such as a nebula or galaxy, is modeled as one typical image pixel sampling a continuous surface brightness. A stellar object is modeled as a Gaussian Point Spread function. The details aren't really important-what matters is that comets are both of these things, and to varying degrees depending on the comet. Some comets look like stars with no visible coma, while others are completely diffuse, with no central bright spot. Most lie somewhere in between. This makes comets really difficult to model.
SkyTools 4 told me that comet 250P/Larsen would be high in the sky at around 3 AM, and with an integrated magnitude of 19.1, SkyTools predicted that it would be a difficult target. In fact, SkyTools predicted that even once I stacked three 4-min exposures the Signal to Noise Ratio (SNR) would only be 8. An SNR of at least 5 is typically required to do fairly accurate astrometry. So SkyTools was predicting that this would be a marginal observation.
And indeed it was! The SNR measured by Astrometrica was 6, which is quite close. This relatively small difference is actually quite remarkable, given how difficult comets are to model. Being able to fairly accurately predict how long of an exposure is required to obtain good astrometry is a rather useful thing!
Incidentally, SkyTools 4 also told me that the comet would only move by 3 pixels over the course of the three exposures, and that it would move by 1 pixel during each of them.
