From: "doobisary" <tjp314@pacbell.net>

Date: November 10, 2011 8:10:19 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Asteroid 2005 YU55 observations?

Hi Milton:

Well, I did manage to SEE it!  I started looking about 10 minutes before it crossed onto the S&T hi res finder chart.  Star-hopped the whole way in Los Angeles 3rd magnitude skies with a nearly full moon!  

I made sure I had the right star fields and started the hunt!  It took me about a half hour after the 'roid crossed onto the chart to find it, though.  But once I did, I was able to track it visually for about 45 minutes.  Man, that sucker was MOVIN'!  Faint, too.  I don't think I would have seen it if it was much dimmer.  I had to use averted vision to relocate it after losing it about 5 times over the 45 minutes.  

A luthier friend of mine from down the street came over with a couple of barley sodas and watched it with me.  It was fun showing such an obscure special-interest subject to a non-astronomer and seeing his reaction to it.  

It was a good evening.  When we finally lost track of the asteroid, I didn't make any attempt to locate it again, because it was already pretty far off the hi resolution chart by that point.

I would never have found it on the ccd, though.  Not unless I'd star-hopped into position first and ambushed the asteroid as it screamed through the field.  I had thought about trying that strategy last night or tonight, but a storm system is coming through and I don't expect to see the sky until Sunday at the earliest.

-Tim.

--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@...> wrote:

Hi Tim;

I was thinking about imaging it, but i can't even figure out where @#% 

$#% it is. Don't forget that because it's closer to us than the moon,  

your latitude and longitude on the globe makes it's location in the  

sky different than shown in S&T and other sites.

With SNP, you have to replace their Asteroid.txt file with the one you  

get from Lowel observatory, which is a 150 meg text file. Then SNP  

will only import the first 15,000 asteroids, so you have to locate  

2005 YU55 in the 150 meg file and move it to the top of the list. PITA.

Equinox Pro already knows where it is, but I updated the MP list anyhow.

However I have a 6 degree Dec difference between where SNP says it is  

and where Equinox Pro says it is. From online stuff and S&T plot, the  

SNP location is junk. Likely old emperis ofr some issue with the file  

format - who knows.

So I got to JPL's ephemerides web site, enter my Lat and Longitude,  

altitude and get it to generate the RA/Dec locations with UTM to the  

minute.

Well it doesn't match either of these, though Equinox is a lot closer.  

There is a 10 arc minute difference on RA and 30' difference Dec  for  

the same time (8 pm my time is +3 UTC).

Since my FOV is 20 arc minutes vertical arc minutes , a +/- 30 arc min  

uncertainty isn't worth my time doing it.

So instead I'm going to do a 4 hour Photometric run on Mag 14.1  

Asteroid Antonia, which I know where it is :)

TTYL..

Milton J. Aupperle

On 8-Nov-11, at 5:45 PM, doobisary wrote:

Okay, that's interesting.  I'd use my DSI Pro III (same exview HAD  

chip as the Grasshopper, I believe), but I can't get Nebulosity to  

link to it on the new Macbook Pro.

I might try a Mogg focal reducer with the Scorpion to get down to f/ 

3, if it doesn't distort too badly.

-Tim.

--- In Astro_IIDC@yahoogroups.com, Milton Aupperle <milton@> wrote:

Hi Tim;

It's moving about 7 arc second per second, or 7 arc minutes per

minute , so it will probably be across your field of view in < 2

minutes. On my AT8 RC Scope (1625 mm FL)  with the 1384x1036

Grasshopper camera (6.25 micron pixels), it will take all of 3  

minutes

to cross the entire FOV.

For Asteroid "Euphrosyne" which is Mag 10.5,  I was using lowest  

gains

(64) and 15 second exposures binned 1x1 with the EXHAD Grasshopper -

LPR Filter and an IR Cut Filter too. With moderately high gains and

4x4 binning, that would have been in the 133 ms exposure range.

So if you just want to capture it, use "Binned 4x4 Monochrome"  for

"Camera Display Format", moderately high gains on the Scorpion and

probably 266 to 1000 ms exposures with a 10" Aperture.  The scorpion

has much smaller pixels and a HAD CCD so it's less sensitive on

several fronts than the EXHAD CCD in the Grasshopper.

As to doing photometric your going to need a much shorter focal  

length

to keep the Constant stars and Asteroid in the FOV to measure it's

changes over time.

HTH..

Milton Aupperle

On 8-Nov-11, at 1:57 PM, doobisary wrote:

Hi all:

I wasn't sure we'd have clear skies tonight, since we had some

really biblical thunderstorms As recently as Sunday night, but it

looks like it will be clear.

Pegasus should be high enough to clear my house from the back yard

by the time I get home and can get set up for imaging, so I plan to

go out and do so.

Since the asteroid is fainter than 11th magnitude, I imagine setting

the exposure time to a few seconds will be in order.  I'll use my

Scorpion 1600x1200 mono camera for the video.  Probably without a

filter, to pull in as many photons as possible.

I'll look over Milton's descriptions of how he did his light curve

work on other asteroids, but I imagine my best strategy will be to

simply start recording "video" and manually track the asteroid as it

screams across the sky for as long as I can (or until I collapse or

fill up my hard drive).

I'll use my 10" f/6 Newtonian on the Tak EM-500 mount for this.  I

need to tweak the collimation on the primary, but the asteroid is

going to be near Altair in the sky so I'll use it to collimate on.

If anyone has any suggestions as to my strategy that I haven't

thought of, please let me know.

-Tim.

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