Re: [guide-user] confusing actual comet data of 21P

Rolf Stadelmaier Sep 18, 2018

Hello Bill,
with comet 21P I experienced another somewhat odd effect:
When 21P is visible in Guide and when zooming in it may happen that the comet disappears at the lower screen border. Then 21P appears at a different position with an offset like the one I described in my earlier post. I found a solution to put this to an end by setting the first line in the file _Guide/asteroid/cometg.dat_ to zero. This because when I delete this file Guide claims: GUIDE needs the GUIDE CD-Rom to run.
No problem so far. I only thaught to let you know.
Kind regards,
Rolf Stadelmaier
Sent: Saturday, September 08, 2018 9:22 PM
Subject: Re: [guide-user] confusing actual comet data of 21P

Hi Rolf,

I think I've got this figured out. Tom's comment about the file
being full of HTML code was the key.

A few years ago, MPC switched from plain old unencrypted HTTP traffic
to "secure" (or at least much more secure) HTTPS traffic. Since then,
if you asked for an unencrypted page, it would silently switch you over
to the secure version. Now, it doesn't do that; it'll give you their
main page instead. Which doesn't have any comet elements in it.

To fix this, download

It should replace an existing file in your Guide folder. _If you don't
get a warning about replacing a file, you aren't putting it in the
correct place_.

I think what happened was that when the "correct" file was clobbered
with meaningless HTML (rather than being updated), Guide fell back on
the IMCCE data. That data is still useful for older comets, but hasn't
been updated for a while now; Guide is quite reliant now on the MPC
file for currently-visible comets.

-- Bill

On 2018-09-06 12:12, 'Rolf Stadelmaier' rostm@... [guide-user] wrote:

> Hello all,
> in
preparation for observing the comet 21P/Giacobini-Zinner the last night I
> downloaded the actual MPC comet data in Guide9. When I slewed my
> to the apropriate coordinates I saw (my camera saw) no comet
is present.
> Further on in a 2-degree neighborhood I found no
> Later on when I compared backuped comet data from around mid
august with
> these actual data I found that the older trajactory and
newer one are
> parallel postponed to another by -0.54 h in RA and +6.33 °
in Dec - that's a
> lot.
> Has anyone else experienced this issue
and/or knows what is going on?
> Best regards from a
confused/frustrated observer,
> Rolf Stadelmaier
> ------------------------------------
> Posted by: "Rolf
Stadelmaier" <rostm@...>
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