Starry Night Enthuisiast 6- Can't Get Comet 252P Linear.

[Suzy]

Hello everyone, I hope someone can help me please?
I've been so frustrated, as I love observing comets and I want to see this comet before it's too late and gone .
It just won't show up in my comet data base.
I update it every time it starts up, but nothing.

If someone can help, it'd be very much appreciated .

[Wodnas (Robert)]

Don't know if this helps.Taken from Sky Safari

Thanks Bob

[Suzy]

Hi Robert, thank you for that. I have Sky Safari as well, and the comet does show up there, but it gives me limited information i.e. how far a comet is from a bright star that will help me to find it. I have an Argo Narvis which is great for popping in the right area, and then I need to-a-hunting. And if possible, in most cases, I prefer to manually find comets. It gives that one-one experience with the sky and is so rewarding when I get it myself.

[OzEclipse (Joe Cali)]

Hi Suzy,
Starry Night certainly don't put all observable comets in their DB. They seem to have lot's of old now unobservable ones but not much current.
I have SN pro v6 same generation as you but different level.

Not sure about enthusiast but in pro you can use the minor planet centre ephemerides service here :

http://www.minorplanetcenter.net/iau/MPEph/MPEph.html to generate orbital elements that can be put into the orbit editor in SNP. I have only tried this once for a NEO and it was very inaccurate but it should work fine for a distant comet. Make sure you check the Starry Night format for the ephemerides to get them in easy to use format.

The numbers are all in the proper format for easy use in Starry Night's
orbit editor. Just click on the word Sun in the planet floater and then
click on add. In the first window that appears select the comet as the type
of object you want to add. Please see the manual for more information.

The orbital information should have the reference plane set at Ecliptic
2000 and the Style should be pericentric. Don't forget to use copy and
paste to ease the input of the orbital data into Starry Night.

This file kindly prepared by the IAU Minor Planet Center & Central Bureau for Astronomical Telegrams.

Num Name Mag. Diam
LINEAR............................. ..17.5 0.0

e................q................N ode................w............... .i..
0.673675....0.996073....190.9811... .....343.2912........10.4047


Tp...............................Ep och
2457462.7785..............2457400.5

Check the starry night plotted position against the generated ephemeris coordinates at a couple of points in time for accuracy.

cheers

Joe

[astroron (Ron)]

Originally Posted by OzEclipse

Hi Suzy,
Starry Night certainly don't put all observable comets in their DB. They seem to have lot's of old now unobservable ones but not much current.
I have SN pro v6 same generation as you but different level.

Not sure about enthusiast but in pro you can use the minor planet centre ephemerides service here :

http://www.minorplanetcenter.net/iau/MPEph/MPEph.html to generate orbital elements that can be put into the orbit editor in SNP. I have only tried this once for a NEO and it was very inaccurate but it should work fine for a distant comet. Make sure you check the Starry Night format for the ephemerides to get them in easy to use format.

The numbers are all in the proper format for easy use in Starry Night's
orbit editor. Just click on the word Sun in the planet floater and then
click on add. In the first window that appears select the comet as the type
of object you want to add. Please see the manual for more information.

The orbital information should have the reference plane set at Ecliptic
2000 and the Style should be pericentric. Don't forget to use copy and
paste to ease the input of the orbital data into Starry Night.

This file kindly prepared by the IAU Minor Planet Center & Central Bureau for Astronomical Telegrams.

Num Name Mag. Diam
LINEAR............................. ..17.5 0.0

e................q................N ode................w............... .i..
0.673675....0.996073....190.9811... .....343.2912........10.4047


Tp...............................Ep och
2457462.7785..............2457400.5

Check the starry night plotted position against the generated ephemeris coordinates at a couple of points in time for accuracy.

cheers

Joe

Hi Joe,I downloaded to sky six the minor planet center comet ephemeris
and comet 252P/LINEAR was wrong, out by at least four degrees.
I downloaded the ephemeris three times and it was wrong on all occasions.
My tablet with SkySafari 4 plus is also out but not as much.
I just think the comet is travelling to fast and too close for the data base to keep up.
The data for other comets was /is correct so that is my only conclusion
I also downloaded it into my Argo Navis with same results.
Cheers
PS
Suzy usually get all other comets downloaded with starry night, so why not 252 LINEAR. ?????

[OzEclipse (Joe Cali)]

Ron,
These errors you mention are why I gave my warning about cross checking the returned ephemerides against the position in your software.

If you enter an observatory code or Lat/Long & Altitude, the MPES will return topocentric ephemerides for your location.

Some software packages only calculate geocentric positions. During close approaches the difference becomes significant. From memory, Starry Night was out by more than 30 degrees for the passage of the NEO DA14. But that was an extreme case - DA14 passed between us and the Moon.

In this case, the 252P comet's range is about 20 million km so the geo/topocentric parallax should be less than 1 minute of arc. Clearly there is a problem with the orbital elements published, their input, or the software's orbital calculation. Joe

[julianh72 (Julian)]

Originally Posted by Suzy

Hi Robert, thank you for that. I have Sky Safari as well, and the comet does show up there, but it gives me limited information i.e. how far a comet is from a bright star that will help me to find it.

Suzy,

Locate and centre the comet (or any target for that matter) in Sky Safari, and then zoom out if necessary to get a wide enough field of view to be useful for star hopping - but don't pan the view. Tap on a nearby bright star that you can use as a star-hopping aid, but don't Centre on it, and then tap on the Object Info icon. Near the bottom of the the left-hand-side information bar, it will show the Angular Separation from the Sun, from your selected target (eg Comet 252P/LINEAR), and from the Chart Centre (which will be the same separation if you don't pan the view).

E.g. as I wrote this (3:00 pm April 15), it tells me that Comet 252P/LINEAR is 3 deg 14 min 44 sec from Magnitude 2.76 Cebalrai (Beta Ophiuchi).

You can repeat this for a few other star-hopping stars, and it should get you sorted pretty well.

The other useful trick is to have Sky Safari show a circle for your finder-scope's FoV, which you can use to simulate what you should see as you star hop using the finder.

Hope this helps!

[sil (Steve)]

Suzy, I was frustrated too with SN7pro and had to rely on skysafari, updating often to get my shot of 252P. Bit of a let down, I do like SN and generally find it very reliable for me. It did come up with another comet nearby which I was going to try for, but a bit more research it had broken up after its last swing past the sun so its magnitude was beyond my reach but SN still had its pre-breakup data

SkySafari proved to have it accurately plotted and helped me line up my DSLR and 252P was dead easy to spot in my first test shot, always a good thing.