bright glint from Mir, Eye-Poppers (tm) public alerts

Walter Nissen (dk058@cleveland.freenet.edu)
Wed, 5 Aug 1998 19:01:17 -0400 (EDT)

Jim Cook sent me the attached report of a Mir OBS on 19980727 UT, which I 
think SeeSatters would like to see. 
 
I occasionally send out e-mail alerts for satellite Eye-Poppers (tm) 
visible from the DC-Baltimore area and the Cleveland area.  Anyone who 
would like to receive a few per year is welcome to ask to be added to my 
lists.  They are very irregular, sometimes 3 in a month, sometimes 1 in 6 
months.  To benefit from the passes mentioned in the alerts, you or your 
loved one has to observe within an area including Philadelphia, Richmond, 
Pittsburgh, Columbus, Detroit, Buffalo and vicinity.  But if you merely 
want to be alerted to the fact that high passes of Mir or shuttles are 
presently occurring at latitude 39 or 41, even people in Europe or Asia 
might sometimes find them useful.  The press release mentioned below was 
one such alert.  Jim Cook also refers below to his own preparation of a 
Mir alert handout for people at the Smithsonian. 
 
Cheers. 
 
Walter Nissen                   dk058@cleveland.freenet.edu 
-81.8637, 41.3735, 256m elevation 
 
--- 
 
The threat is more powerful than the execution. 
 
--- 
 
While I missed Mir's pass on Friday evening, here in the DC area (the pass 
which you sent out your press release for), I did however watch it as it 
passed high overhead tonight (about 9:15 PM, Sunday). 
 
I have to say this was the most unusual pass I have ever seen for Mir, even 
after watching it for a number of years now.  While my Mac's Orbitrack 
indicated it was sunlit the entire pass, it didn't become visible to the naked 
eye until it began approaching the meridian, nearing perhaps 60-65 degrees up. 
 
And then the fireworks started. 
 
I have a DOS emulator on my Mac, allowing me to run Quicksat.  Quicksat had 
predicted Mir would brighten to -2.7 magnitude.  No way.  This went way beyond 
that.  WAY BEYOND that.  The flare off Mir I saw tonight would have rivaled 
the best of Iridium flares I've ever seen, including the best of the three -7 
magnitude flares I've seen.  And this was during mid twilight, on top of it. 
 
The day was overcast until late afternoon and when it finally cleared, the sky 
still had an eerie sort of haze to it.  At 9:10 when I went out, I spotted the 
crescent moon, a dull orange-yellow color, no doubt from that summer 
Washington haze.  I spotted Arcturus and the summer triangle stars with no 
trouble (Deneb was a bit hard to find, though). 
 
Mir was supposed to pass within 5 degrees of Arcturus at about 9:16.  I never 
saw it.  Then it just appeared, about 10 degrees along its path after passing 
Arcturus, as it rose toward the meridian.  A few seconds after it finally 
appeared, it was brighter than Arcturus, as Quicksat predicted (though I 
expected it to have appeared long before it did).  But then it just lit up. 
Seriously, I'm talking magnitude -7 or better.  I've never seen Mir do that. 
I'm guessing it was about 9:17 on the nose of very close to it once this "Mir- 
flare" began.  And like a good Iridium flare, it lasted a good 8 seconds or 
more before settling back down to typical -1 magnitude, and then fading into 
the haze as it descended to the NE a minute or so later. 
 
I don't know what to make of this pass.  On the one hand, it didn't show up at 
all for the first half, as both Orbitrack and Quicksat predicted it would. 
And that fact had me really worried ... .  Because when it did finally show, 
it was absolutely impossible to miss.  I'm not sure that wasn't the 
brightest spacecraft I've ever seen, Iridium flares included. 
 
--- 
 
That was his original report.  I responded in draft form and he replied in 
a message apparently corrupted by some sort of messy AOL e-mail glitch 
which has greatly delayed this message.  Edited to something like what I 
take to be its intended form, it follows: 
 
--- 
 
Date: Tue Jul 28 11:36:21 1998 
 From CmdrJaycee@aol.com 
Subject: Re: re: See the Space Station !!! 
To: dk058@cleveland.Freenet.Edu 
 
Hello Walter - 
 
In a message dated 7/28/98 9:12:48 AM, dk058@cleveland.Freenet.Edu writes: 
 
>One of the reasons I am behind in my responses to you is that you ask very 
>challenging questions. 
 
I'll take that as a compliment ;-) 
 
>I have previously written about how there are more predictable objects 
>than satellites, objects like planets, comets, etc.  I think I said 
>something about shooting fish in a barrel. 
 
That was some time ago - I understood what you were trying to say.  I've 
since been on SeeSat long enough to realize that you get novices jumping 
in from time to time wanting to do just that - shoot fish in a barrel. 
And in some respects that was true of my question at the time.  My 
interest in the "easy ones" back then was partly do to my having just 
gotten started in satellite spotting at a more "active" level and wanting 
to be able to start with the easy, reliable ones and work up from there. 
But I was also interested in the easiest, most reliable ones because I 
help out a public stargazing programs at Black Hill Park in upper 
Montgomery County and I was looking for some reliably bright satellites to 
keep tabs on for possible use during our events, so people who came out 
those evenings might have a good chance of spotting some of them. 
 
(In fact, I still remember there was one event some years ago, long before 
I even heard of SeeSat, that involved people from a home for the disabled, 
or perhaps from a nursing home, and there was one elderly gentleman who 
could not get up from his wheel chair to look through the scopes we had 
set up, nor could he get close enough in the chair to look the eye piece, 
even when rotated downward, without his wheel chair banging into the 
scope's tripod and knocking the object out of the field of view.  I felt 
terrible for him - he must have felt so left out.  And then one cue, I 
spotted a nice satellite passing overhead and quietly pointed it out to 
him - and he cracked a silent grin, feeling perhaps that he had finally 
seen something the others hadn't, evening things up a bit.) 
 
>According to reports appearing in SeeSat-L, Mir has recently been much more 
>glinty and much more unpredictable than previously.  I have seen and reported 
>this myself, though I haven't seen anything as extreme as you report, 
>certainly not a really dim segment of a pass, nor any glint so bright. 
 
I can't say this for sure, but it would not at all surprise me if the dim 
segment may have resulted from the haze that evening.  I don't recall 
seeing Spica for example (though it may have been behind some trees), but 
haze has to be worse the lower in the sky one goes, so perhaps it was 
dense enough to hide Mir until it climbed sufficiently.  (What I can't 
explain, though, is why, when it finally did appear, it did so suddenly, 
brighter than Artcurus, almost out of nowhere.) 
 
>These reports have to be somewhat disturbing to those of us who send out 
>public notices, who have long treasured Mir's extreme brightness and 
>nearly unparalleled predictability. 
 
I wouldn't stop sending them out just yet.  These irregularities may just 
be just that - irregular, and perhaps will disappear over time, with Mir 
returning to its usual steady self.  Even so, I think as long as it does 
appear somewhere along its predicted path, people will still go out and 
try to find it.  They just need to be reminded that if it doesn't show at 
a predicted time and place in the sky, to keep moving along with it and 
not get hung up at the some point in the sky waiting for it to appear. 
That was my big fear when I put in my handout that Mir would pass within 5 
degrees of Arcturus and that this would be a good way to find it - that 
is, find Arcturus and wait for Mir to pass by.  But the risk was, if Mir 
didn't appear - people would keep looking at Arcturus even though Mir had 
passed it.  I certainly expected Mir to have become visible by then, so, 
yes, when it didn't, speaking as the person who made up the hand out, that 
was indeed a bit distrubing.  While I hope some people had the sense to 
check their watches and realize Mir must have passed Arcturus, and so 
moved on to the next checkpoint in the sky, I'd bet many didn't and got 
hung up at Arcturus.  The saving grace was that I had noted that almost a 
minute after passing Arcturus, at about 9:16:45, it was predicted to reach 
-2.7 magnitude (according to Quicksat), making it easily the brightest 
point in the sky.  And that, thankfully, turned out to be an serious 
understatement. 
 
>When you say you've seen three -7 mag Iridial glints, I fear that you mean 
>3 glints which were predicted to be -7. 
 
Yes, that is correct.  My language should have been more precise.  Perhaps 
I should also mention that I have seen a few more Iridium flares predicted 
to have reached -6 and -5 magnitude, in addition to the three I mentioned; 
in all, I've seen perhaps a dozen predicted to have been from between -5 
and -7.  I may not have actually seen a full blown -7 magnitude flare 
among them, but I have seen a good cross-section of a dozen bright flares. 
The reflection I saw off of Mir Sunday evening was as bright as the 
brightest of the Iridium flares I've seen so far. 
 
What leads me to feel Mir had to be in that same range was simply that 
Arcturus was nearby in the sky, rather subdued in the haze and twilight, 
and yet Mir still lit up as bright as the brightest Iridium flare I could 
recall seeing.  Having seen Venus many times under similar conditions over 
the years (that is, under typical Washington haze during mid-twilight), I 
would guess Venus would have been somewhere between Mir and Arcturus in 
brightness.  In other words, had Venus been in the sky, from past 
experience, there's no way I can imagine it would have stood out that much 
brighter than Arcturus as Mir did, under those same conditions. 
 
>When I estimate -6, I suppose I could be a couple of magnitudes off. 
 
I understand.  I don't pretend to be good at estimating magnitudes, even 
as an amateur astronomer for some 20 years now, and particularly when they 
go off the scale into uncharted territory, as the Iridium flares do, and 
as Mir did Sunday night, at least from my own experience.  So when I say I 
think it might have been -7 magnitude based on the brightest Iridium 
flares I've seen, like you, I confess I'm still guessing.  All I can say 
for sure is that Mir's brightness Sunday evening was unprecedented in my 
own experience.  What troubles me particularly, though, is the conditions 
of the sky at the time.  I think it's safe to say that haze and twilight 
considerably dim stars and presumably very bright satellites are no 
exception.  That was the case at about quarter past nine here the DC area 
Sunday night when Mir's pass occurred.  I saw only a few stars in the sky 
(each of 1st magnitude) along with a dull orange-yellow crescent moon.  So 
that was my sky's limit at the time - murky (as I mentioned, Deneb, 
perhaps 15-or-20 degrees away was just about the limit of my vision at the 
time).  Yet here comes Mir out of nowhere and shortly after passing the 
meridian, perhaps 70 degrees up, suddenly, for ten seconds or so, starts 
blazing away as bright as the brightest Iridium flare I could recall 
seeing (which, in contrast, was under clear, dark conditions).  That's why 
I'm a bit concerned I may even have UNDERestimated it's brightness.  But 
again I freely admit, I don't really know how bright it appeared.  If 
Quicksat was correct, that at that point it was reaching it's predicted 
-2.7 magnitude - and at the same time a very bright glint occurred, 
perhaps the two combined could have caused it to appear as bright as a 
good Iridium flare? 
 
Anyway, I hope this has help.  I really can't say Mir reached -7 
magnitude, but, to use your words, I am comfortable saying I really think 
it was brighter than Venus, under similar conditions. 
 
Talk to you soon, Walter. 
 
- Jim Cook in Germantown, MD, 39N, 77W 
 
--- 
 
Then Jim commented further: 
 
--- 
 
Date: Tue Jul 28 21:06:56 1998 
 From CmdrJaycee@aol.com 
Subject: AOL Tech Reply / Mir Flares 
To: dk058@cleveland.Freenet.Edu 
 
Hello Walter - 
 
Just wanted you to know that I saw the following on today's SeeSat-L Digest: 
 
------ 
>Date: Tue, 28 Jul 1998 15:12:01 +0100 
>From: brixham <brixham@rmplc.co.uk> 
>To: SeeSat-L@cds.plasma.mpe-garching.mpg.de 
>Subject: mir flares 
> 
>Perhaps the following from mirnews.431 explains the bright flares from 
>Mir at present 'one of the solarpanels of the Spektr module does not 
>produce enough energy due to the malfunction of the driver which has to 
>change the angle of that panel. (To eliminate this problem the crew of 
>the next expedition has to execute an internal spacewalk -IVA- inside 
>Spektr).' 
> 
>Regards Steve Daniels 
>I.T. Technician 
>Brixham Community College 
>50.245N 3.34W 210ft 
------ 
 
I wonder if this same panel could explain why Mir did not appear as it rose 
Sunday night as well, perhaps being backlit or otherwise blocking the sunlight 
off other surfaces from being seen? 
 
--- 
 
I close with one final comment to Jim's comments: 
 
The fact that Mir was difficult to pickup early in the pass, Jim points 
out, may be predominently due to the local haze.  I can well understand 
this.  The gradient into a cloud can be extremely difficult to judge, 
even if it is very thin and the sky very dark.