25 replies to this topic

[happylimpet]

Clear sky - poor seeing. Whadda you do???

 

So I did too really long runs imaging Sedna (my 2nd or 3rd attempt) and Varuna, an easier brighter backup.

 

12" skywatcher 300p at f4.5 and Atik 460ex unfiltered at 2x2 binning. EQ8 mount.

 

Both are composed of 10 second subs, 1200 and 1500 respectively!  4 hours and 5 hours. My sky is so bright that these are sky limited so nothing to be gained in longer exposures except guiding errors. Though bearing in mind the gusty wind the system worked a treat.

 

Used deepskystacker in comet mode and calculated positions for a fictitious comet for it to track, editing the .info files DSS makes. Made all the difference for Sedna though Varuna was a clear track in the normally stacked version.

 

Google these objects - they're both interesting especially Sedna - check out how big it's orbit is!!!

 

Sedna, at 86AU and Mag 20.9:

 

Varuna, Mag 20.1, at 43 AU out:

 

Varuna (normal stack):

 

 

[Kokatha man]

A good feat Nick!

How do you find the EQ8..? I bit the bullet & purchased one about 2 weeks ago & used it for the very first time the morning before today...handles the C14 effortlessly (hoping to swing a larger scope sometime!) but the amount of steel in the pier-type base etc meant I couldn't use my normal means of getting its' N-S set with the old surveying compass I employ...I'm making a much longer aluminium "arm" now to distance the compass about 1200mm from the pier top so I don't get interference!

[happylimpet]

A good feat Nick!

How do you find the EQ8..? I bit the bullet & purchased one about 2 weeks ago & used it for the very first time the morning before today...handles the C14 effortlessly (hoping to swing a larger scope sometime!) but the amount of steel in the pier-type base etc meant I couldn't use my normal means of getting its' N-S set with the old surveying compass I employ...I'm making a much longer aluminium "arm" now to distance the compass about 1200mm from the pier top so I don't get interference!

 

Yes I saw somewhere that youve taken the plunge! Congratulations!!!

 

I love it!!!! Though my old mount was completely agricultural! A 4arcmin periodic error, and a fixed speed motor drive, no dec slow motion....so anything is a huge step up!

 

But regardless, its a sweet sweet mount. Its worked like a treat since I got it. Revolutionised every aspect of my imaging, though reduced my visual as Im taking advantage of the new possibilities.

 

My scope weighs 27kg without cameras (I think) and it handles it effortlessly. Even in the wind. You'll appreciate it Im sure. You had an EQ6 before no???

 

Ive got the polar scope - which I recommend. Its got a reticule for the sigma octantis nonsense you guys have to deal with!!!

[Kokatha man]

...certainly agree with the sentiments you express Nick...well, from one morning! (& too much time the night before faffing around...)

 

We intend lugging it around & I don't find any problems carrying the base or head around even at 66...it's that durn lot of steel upsetting our compass that annoyed me mainly..!

 

My old surveyor's compass reads 0.25° easily so it is a really good means of setting N-S when taking Mag. Dev. into account...with the EQ6 I used a short piece of timber about 600mm long with the compass on one end & the "sight" (a white nail!) on the other, securing it with 2 bolts to the mount head where the Az. spigot fits into either of 2 threaded holes...

 

The Wixey sets a pretty good Dec angle I might add...

 

With the EQ8 I'll have to use the 2 X 8mm Az locking bolt threads in an E-W mode of aligning...but I've needed to purchase a 1.8M length of box-section ally extrusion so I can position the compass well away from magnetic interference via the pier steel: pity they didn't make that from a mix of stainless steel & ally like the smaller mounts - which meant magnetic interference was negligible...

 

We expect windy conditions won't worry this mount etc so much & we've already noticed that the "damping-down" time after adjusting collimation screws is very quick due to the far greater stability...

 

We don't worry too much about razor PA'ing with the view that a bit of wandering is actually good for planetary stacks - but without the use of the compass & virtually eyeballing Geo. N-S the other night we noticed with large ROI the star during collimation displayed very little drifting...& Jove in a 512X400 ROI at f22 with the C14 was easy to keep in the really confined space of said ROI...so all in all very promising "first light!"

 

I'll probably do a 1 or 2-star alignment when we get daring & use the much more ergonomic Alt/Az adjusters this mount has compared to the EQ6 to centre the stars I select instead of using the slew buttons before confirming their positioning...this should produce a pretty good PA if we get that picky...& I do like the easy "Home park" function, even for us "plonk & go" types!

[happylimpet]

Sounds like a great start. Never thought of the magnetic effect of the mount!

 

I set mine up every night, total weight 110kgs! I'm 41 so encouraged to hear youre managing OK too!

 

Yeah PA isnt something I lose sleep over. But it is sweet when you set a small ROI for Neptune and it doesnt stray more than 5" either side in 20 mins!!!! but thats largely down to PA luck for me.

 

One star alignment on Lambda Aquarii and then hopping to Neptune (for example) works amazingly well. Pointing is very good.

 

Cool beans man! Excited for you! Excited for me too! What a time to be alive!

Edited by happylimpet, 10 December 2015 - 06:26 PM.

[DesertRat]

Hi Nick,

 

That is very nice! 

 

Sedna is really out there.  Wow!  The Sun must be just a really bright star from that place.  Great to have something to do when turbulence is excessive.

 

I like polar alignment done well enough only to keep an object in view or at least close during tea breaks.  I think Darryl is correct, a little wandering may help in some cases.  Usually the atmosphere helps enough in dithering for Emil's debayer approach!  More important I think is good balancing to help the mount out.  Sounds like the EQ8 is pretty good.

 

Glenn

[Mike Phillips]

Without doing the calculations myself I have to say I'm quite surprised to see so much motion from Varuna as its listed as 0.037 "/min.  I know when I shot Eris that even over three nights it didn't move much at all!  Great work!  Do you submit to MPC?

 

Mike

[Kokatha man]

Hi Nick,

 

That is very nice! 

 

Sedna is really out there.  Wow!  The Sun must be just a really bright star from that place.  Great to have something to do when turbulence is excessive.

 

I like polar alignment done well enough only to keep an object in view or at least close during tea breaks.  I think Darryl is correct, a little wandering may help in some cases.  Usually the atmosphere helps enough in dithering for Emil's debayer approach!  More important I think is good balancing to help the mount out.  Sounds like the EQ8 is pretty good.

 

Glenn

 

Yes, I've often wondered why we have never experienced the problems some folks have, not only matrix grid manifestations but also (from a pretty ignorant understanding I might add!    ) we don't seem to encounter other camera image-patterning etc issues, for want of a better description that some camera users have reported in the past...nfi tbh but we do let the planets wander around appreciably - maybe we'll find too much tracking accuracy counter-productive!

 

Just about all set to test my new alloy sighting gauge in a few minutes - I think I managed good accuracy in drilling all the holes with my limited machine workshop facilities, especially the larger 20mm one that accepts the survey compass..!

 

EDIT: ps: speaking of weight, I'm fortunate that an old buddy who occasionally posts here gave me parts of an old mount assembly - & the 6kgm or so counterweight it had has the same bore as the EQ8's weights...I needed that with the 2 X 10kgm ones to balance: thanks for that Rob!  

Edited by Kokatha man, 10 December 2015 - 10:08 PM.

[blackadder1620]

How did you know you had it in the ep? Its so dim and tiny. I've always wondered about finding objects out there, even Pluto seems a stretch to find for me. Clear skies.

[geminijk]

Wow, that is fantastic to be able to capture the KBOs. Thank you for sharing, its amazing to see how far amateur astronomy has come in a relatively short time. 

 

John

[John Boudreau]

Outstanding work, Nick! 

 

 

Something I hope to eventually getting around to do myself.

[happylimpet]

Without doing the calculations myself I have to say I'm quite surprised to see so much motion from Varuna as its listed as 0.037 "/min.  I know when I shot Eris that even over three nights it didn't move much at all!  Great work!  Do you submit to MPC?

 

Mike

 

I dont have my calc's here but its of the order of 1-2"/hr...but this was 5hours of exposure! Your numbers look about right. The motion is pretty much all due to the Earth so its pretty much inversely proportional to distance, hence more trailing with Varuna than with Sedna.

 

Positions were bang on relative to NASA HORIZONS which is where I got the coords, and that combined with WikiSky told me where to look. I dont know enough about astrometry to report an accuate position!

 

 

How did you know you had it in the ep? Its so dim and tiny. I've always wondered about finding objects out there, even Pluto seems a stretch to find for me. Clear skies.

 

I star hopped (with the CCD) from a nearby bright star (HD catalogue) about 1 FOV away and compared the field to the known location from my wikisky printout. No chance of seeing the bugger!

[happylimpet]

ONE MORE THING! If you look at the last image, where Varuna is trailed, you'll notice that its far from constant in brightness through the trail.  Its dimmer in the middle with bright ends. Apparently Varuna is very elongated with a rotation period of 6.34 hrs (a little more than the total exposure time) and an amplitude of 0.28 magnitudes, and so it seems this shows the varying brightness as it spins!

 

You can tell this isnt due to varying atmospheric conditions, as in the image tracked on Varuna itself, the star trails dont show any such variation along their length.

 

Sweet!

Edited by happylimpet, 11 December 2015 - 04:59 AM.

[Kokatha man]

...with that sort of spin maybe it should've been called "Varooma"..!

 

A real "egg" apparently & a typical cubewano..!  

[happylimpet]

...with that sort of spin maybe it should've been called "Varooma"..!

 

A real "egg" apparently & a typical cubewano..!  

 

Hahaha but I dont think that sort of humour is permitted on a serious site like this!!!

[Mike Phillips]

Not to be a naysayer, but I'd like to help you get to the bottom of these.  Can you give me the time frames for these and more details about your CCD, optics etc?  I don't think you got what you were after.  My doubt stems from having a 14" and cooled CCD and chasing beyond mag 19 is quite challenging for me.  I think you missed

 

 

I'd like to help you find what asteroid you actually DID catch, but I'm guessing it's not a KBO.

 

Mike

 

EDIT - You're within reach of that magnitude, but Varuna hasn't been in your FOV nor do I think it will be.  You certainly caught something, but I'm guessing a main belt or NEO based on what little I do know of these matters...  Great work, it's quite a faint limiting magnitude.

 

EDIT2: Here's the MPC predictions from today onwards, and it really doesn't move much...

 

(20000) Varuna

Display all designations for this object / Show naming citation / # of variant orbits available = 3

Perturbed ephemeris below is based on 20-opp elements from MPO 333003. Last observed on 2015 Mar. 13.

Discovery date : 2000 11 28
Discovery site : Kitt Peak
Discoverer(s) : Spacewatch

Further observations? Not necessary for orbit improvement.

20000              [H= 3.6]
Date       UT      R.A. (J2000) Decl.    Delta     r     El.    Ph.   V      Sky Motion       Uncertainty info
            h m s                                                            "/min    P.A.    3-sig/" P.A.
2015 12 12 000000 08 08 41.2 +26 35 12  43.024  43.787  140.4   0.8  20.1    0.038   292.0       N/A   N/A / Map / Offsets
2015 12 13 000000 08 08 37.4 +26 35 32  43.013  43.787  141.4   0.8  20.1    0.038   291.7       N/A   N/A / Map / Offsets
2015 12 14 000000 08 08 33.6 +26 35 52  43.003  43.787  142.4   0.8  20.1    0.039   291.4       N/A   N/A / Map / Offsets
2015 12 15 000000 08 08 29.6 +26 36 13  42.993  43.787  143.4   0.8  20.1    0.039   291.2       N/A   N/A / Map / Offsets
2015 12 16 000000 08 08 25.7 +26 36 33  42.983  43.787  144.4   0.7  20.1    0.040   290.9       N/A   N/A / Map / Offsets
2015 12 17 000000 08 08 21.6 +26 36 54  42.973  43.787  145.4   0.7  20.1    0.041   290.6       N/A   N/A / Map / Offsets
2015 12 18 000000 08 08 17.5 +26 37 15  42.964  43.787  146.5   0.7  20.1    0.041   290.4       N/A   N/A / Map / Offsets
2015 12 19 000000 08 08 13.3 +26 37 35  42.955  43.788  147.5   0.7  20.1    0.042   290.1       N/A   N/A / Map / Offsets
2015 12 20 000000 08 08 09.1 +26 37 56  42.946  43.788  148.5   0.7  20.1    0.042   289.9       N/A   N/A / Map / Offsets
2015 12 21 000000 08 08 04.8 +26 38 17  42.937  43.788  149.5   0.7  20.1    0.043   289.7       N/A   N/A / Map / Offsets
2015 12 22 000000 08 08 00.4 +26 38 37  42.929  43.788  150.5   0.6  20.1    0.043   289.5       N/A   N/A / Map / Offsets
2015 12 23 000000 08 07 56.0 +26 38 58  42.921  43.788  151.5   0.6  20.1    0.044   289.2       N/A   N/A / Map / Offsets
2015 12 24 000000 08 07 51.6 +26 39 19  42.913  43.788  152.5   0.6  20.1    0.044   289.0       N/A   N/A / Map / Offsets
2015 12 25 000000 08 07 47.0 +26 39 40  42.906  43.788  153.5   0.6  20.1    0.045   288.8       N/A   N/A / Map / Offsets
2015 12 26 000000 08 07 42.5 +26 40 01  42.899  43.788  154.5   0.6  20.1    0.045   288.6       N/A   N/A / Map / Offsets
2015 12 27 000000 08 07 37.9 +26 40 21  42.892  43.789  155.5   0.5  20.1    0.046   288.4       N/A   N/A / Map / Offsets
2015 12 28 000000 08 07 33.2 +26 40 42  42.885  43.789  156.5   0.5  20.1    0.046   288.3       N/A   N/A / Map / Offsets
2015 12 29 000000 08 07 28.5 +26 41 03  42.879  43.789  157.5   0.5  20.1    0.046   288.1       N/A   N/A / Map / Offsets
2015 12 30 000000 08 07 23.7 +26 41 23  42.873  43.789  158.5   0.5  20.1    0.047   287.9       N/A   N/A / Map / Offsets
2015 12 31 000000 08 07 18.9 +26 41 44  42.867  43.789  159.5   0.5  20.1    0.047   287.7       N/A   N/A / Map / Offsets
2016 01 01 000000 08 07 14.1 +26 42 05  42.861  43.789  160.5   0.4  20.1    0.047   287.5       N/A   N/A / Map / Offsets

 

 

It's outside your fov

Edited by Mike Phillips, 12 December 2015 - 05:35 PM.

[happylimpet]

Not to be a naysayer, but I'd like to help you get to the bottom of these.  Can you give me the time frames for these and more details about your CCD, optics etc?  I don't think you got what you were after.  My doubt stems from having a 14" and cooled CCD and chasing beyond mag 19 is quite challenging for me.  I think you missed

 

 

I'd like to help you find what asteroid you actually DID catch, but I'm guessing it's not a KBO.

 

Mike

 

EDIT - You're within reach of that magnitude, but Varuna hasn't been in your FOV nor do I think it will be.  You certainly caught something, but I'm guessing a main belt or NEO based on what little I do know of these matters...  Great work, it's quite a faint limiting magnitude.

 

EDIT2: Here's the MPC predictions from today onwards, and it really doesn't move much...

 

(20000) Varuna

Display all designations for this object / Show naming citation / # of variant orbits available = 3

Perturbed ephemeris below is based on 20-opp elements from MPO 333003. Last observed on 2015 Mar. 13.

Discovery date : 2000 11 28
Discovery site : Kitt Peak
Discoverer(s) : Spacewatch

Further observations? Not necessary for orbit improvement.

20000              [H= 3.6]
Date       UT      R.A. (J2000) Decl.    Delta     r     El.    Ph.   V      Sky Motion       Uncertainty info
            h m s                                                            "/min    P.A.    3-sig/" P.A.
2015 12 12 000000 08 08 41.2 +26 35 12  43.024  43.787  140.4   0.8  20.1    0.038   292.0       N/A   N/A / Map / Offsets
2015 12 13 000000 08 08 37.4 +26 35 32  43.013  43.787  141.4   0.8  20.1    0.038   291.7       N/A   N/A / Map / Offsets
2015 12 14 000000 08 08 33.6 +26 35 52  43.003  43.787  142.4   0.8  20.1    0.039   291.4       N/A   N/A / Map / Offsets
2015 12 15 000000 08 08 29.6 +26 36 13  42.993  43.787  143.4   0.8  20.1    0.039   291.2       N/A   N/A / Map / Offsets
2015 12 16 000000 08 08 25.7 +26 36 33  42.983  43.787  144.4   0.7  20.1    0.040   290.9       N/A   N/A / Map / Offsets
2015 12 17 000000 08 08 21.6 +26 36 54  42.973  43.787  145.4   0.7  20.1    0.041   290.6       N/A   N/A / Map / Offsets
2015 12 18 000000 08 08 17.5 +26 37 15  42.964  43.787  146.5   0.7  20.1    0.041   290.4       N/A   N/A / Map / Offsets
2015 12 19 000000 08 08 13.3 +26 37 35  42.955  43.788  147.5   0.7  20.1    0.042   290.1       N/A   N/A / Map / Offsets
2015 12 20 000000 08 08 09.1 +26 37 56  42.946  43.788  148.5   0.7  20.1    0.042   289.9       N/A   N/A / Map / Offsets
2015 12 21 000000 08 08 04.8 +26 38 17  42.937  43.788  149.5   0.7  20.1    0.043   289.7       N/A   N/A / Map / Offsets
2015 12 22 000000 08 08 00.4 +26 38 37  42.929  43.788  150.5   0.6  20.1    0.043   289.5       N/A   N/A / Map / Offsets
2015 12 23 000000 08 07 56.0 +26 38 58  42.921  43.788  151.5   0.6  20.1    0.044   289.2       N/A   N/A / Map / Offsets
2015 12 24 000000 08 07 51.6 +26 39 19  42.913  43.788  152.5   0.6  20.1    0.044   289.0       N/A   N/A / Map / Offsets
2015 12 25 000000 08 07 47.0 +26 39 40  42.906  43.788  153.5   0.6  20.1    0.045   288.8       N/A   N/A / Map / Offsets
2015 12 26 000000 08 07 42.5 +26 40 01  42.899  43.788  154.5   0.6  20.1    0.045   288.6       N/A   N/A / Map / Offsets
2015 12 27 000000 08 07 37.9 +26 40 21  42.892  43.789  155.5   0.5  20.1    0.046   288.4       N/A   N/A / Map / Offsets
2015 12 28 000000 08 07 33.2 +26 40 42  42.885  43.789  156.5   0.5  20.1    0.046   288.3       N/A   N/A / Map / Offsets
2015 12 29 000000 08 07 28.5 +26 41 03  42.879  43.789  157.5   0.5  20.1    0.046   288.1       N/A   N/A / Map / Offsets
2015 12 30 000000 08 07 23.7 +26 41 23  42.873  43.789  158.5   0.5  20.1    0.047   287.9       N/A   N/A / Map / Offsets
2015 12 31 000000 08 07 18.9 +26 41 44  42.867  43.789  159.5   0.5  20.1    0.047   287.7       N/A   N/A / Map / Offsets
2016 01 01 000000 08 07 14.1 +26 42 05  42.861  43.789  160.5   0.4  20.1    0.047   287.5       N/A   N/A / Map / Offsets

 

 

It's outside your fov

Hi Mike

 

I welcome healthy skepticism! However Im confident about this.

 

The coords came from the NASA Horizons system which is generally found to be very precise.  I know using WIkisky to locate the coords on the sky might raise some eyebrows, but again, Ive always found it to be exact.

 

The movement is EXACTLY as horizons predicted, otherwise the aligned stack wouldnt have worked. It cant be a main belt asteroid or the movement would have been radically different; certainly much faster. The success of the aligned stack method (which was based entirely on calcualtions of the predicted movement,not on anything observed in the images) is, i would say, proof of the identification, not to mention the position being exactly right!

 

I find I can get to Mag 19 pretty easily with 1 hr of stacks.  Ive done it many times, ie 22nd mag gravitationally lensed images of a high redshift quasar, Sycorax (moon of Uranus) etc. So getting to 20-21 is no great shakes. It just takes a few hours!

 

Sedna images were 8/dec/2015 2014-9/dec/2015 0037

Varuna 9/dec/2015 01:16 to 06:34

 

Subs were 10 secs (as wind was very strong and gusty and this is sky limited anyhow).

 

So we have

 

1 exact position

2 perfect speed/dirn on sky

3 brightness in line with expectations.

 

i could even add the variation of varuna's brightness in line with its known variation and period, but thats just the icing on the cake for me!

 

Cheers

 

N

[Mike Phillips]

I think my projection was off, great work!  

 

 

I'd suggest you look into the software package astrometric and also join the yahoo group MPML as you've got the skills to contribute!  

 

Mike

Edited by Mike Phillips, 12 December 2015 - 06:16 PM.

[happylimpet]

The offset of your position from your plate centre is 10 seconds of arc in RA = 150" =2.5'

In Dec it's 2'6"

 

So you have demonstrated that Varuna is within my FOV, for which I thank you.

 

I've been in this game long enough to be able to find stuff!

[Mike Phillips]

My CdC always flips my coordinates on me and I forget to flip them back!!!  I checked in MPC and it seemed far enough from your center I was doubtful!  I'm quite impressed you caught it's motion over a few hours.  I had Eris over 3 nights that I still need to finish processing but I've had issues flipping multi-night images in astrometica.

 

Mike

[GA-HAMAL]

Clear sky - poor seeing. Whadda you do???
 
So I did too really long runs imaging Sedna (my 2nd or 3rd attempt) and Varuna, an easier brighter backup.
 
12" skywatcher 300p at f4.5 and Atik 460ex unfiltered at 2x2 binning. EQ8 mount.
 
Both are composed of 10 second subs, 1200 and 1500 respectively!  4 hours and 5 hours. My sky is so bright that these are sky limited so nothing to be gained in longer exposures except guiding errors. Though bearing in mind the gusty wind the system worked a treat.
 
Used deepskystacker in comet mode and calculated positions for a fictitious comet for it to track, editing the .info files DSS makes. Made all the difference for Sedna though Varuna was a clear track in the normally stacked version.
 
Google these objects - they're both interesting especially Sedna - check out how big it's orbit is!!!
 
Sedna, at 86AU and Mag 20.9:

For comparison, my photo of the day 09-12-2015

[happylimpet]

My CdC always flips my coordinates on me and I forget to flip them back!!!  I checked in MPC and it seemed far enough from your center I was doubtful!  I'm quite impressed you caught it's motion over a few hours.  I had Eris over 3 nights that I still need to finish processing but I've had issues flipping multi-night images in astrometica.

 

Mike

 

Ha no worries, sorry for being a bit tetchy there! Bit of a night last night and got a terrific headache.  

 

Its a good thing we have people doing checks and so forth on here to be honest, makes sure we're all on top of our game and not making spurious claims!

[happylimpet]

 

For comparison, my photo of the day 09-12-2015

 

Ah thats cool, is it coincidence you imaged it the same day?

Im guessing you have a bigger scope as you seem to have got less trailing so presumably much shorter exposure time.

[happylimpet]

I think my projection was off, great work!  

 

I'd suggest you look into the software package astrometric and also join the yahoo group MPML as you've got the skills to contribute!  

 

Mike

 

Cheers Mike.  I downloaded astrometrica a while back but havent got round to using it yet! Maybe i'll have a play now.

 

I could definitely get drawn into this field.

 

I checked the link you posted for mpchecker to see what else was in the FOV, and its got me started!!!