October 30th, 2007 (morning) 17P/Holmes

I have been taking a few snapshots over the last few days and produced a composite showing the comet’s growth.

Additional information can be found here.

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October 29th, 2007 Dual Iridium Flare

Dual Iridium Flare Near Victoria Minnesota

October 29th, 2007 19:55:46/19:56:28 CDT(UTC-5) Iridium 59/90

Daniel Crawford who does flare predictions up to a month ahead of time sent me an e-mail on 10/6 alerting me to another opportunity for dual flares on Halloween (10/31 – a different webpage if it’s not Cloudy). Tony Perkins found and alerted me of this opportunity 10/29 dual iridium flare on 10/24.

Tony had previously published centerline maps which I would link here but, they do not appear to be up at the present time but, I think if your within a half mile West or East of 93.6611° W you will get a dual flare with 42 seconds of separation (so were maybe talking a 60 second exposure. I downloaded the latest elements for the iridium’s from Norad this afternoon, the current predictions for Victoria are as follows;

Flare Details

Iridium flares / Orbitron 3.71 / www.stoff.pl
Orbitron
========
Location : Victoria Flare 1029 (93.6611° W, 44.8570° N)
Time zone : UTC -5:00
Search period : 2007-10-29 19:55:00
2007-10-29 19:59:00
Conditions : Maximum sun elevation = -5 deg
Minimum sat elevation = 10 deg
Illumination required
Minimum magnitude = 3.0

Time Sat Azm Elv Range A D Mag S.Azm S.Elv
—————————————————————-
2007-10-29 19:55:46 59 20.5 39.7 1143 L A -7.8 270.2 -19.7
2007-10-29 19:56:28 90 ? 21.0 41.0 979 L A -8.2 270.3 -19.8
Astronomical Twilight begins at 19:47 – it will be dark
Moon Rise is at 8:35 with the moon rising at 8:35pm 87% illuminated. (it will be really dark in the middle of nowhere, you could get a nice star trail shot, Polaris is just to the left of the flare locations).

Strategy

I spent some time looking thru goggle earth for a good area along the centerline North and South. I eliminated ground targets (lake Minnetonka lakes) due to the fact, I will be using a narrower field of view. Winds this evening will be 6mph from the SSE(consider wind in target selection, trees blowing, long exposure, blurred), might have some clouds but, should be clear, if I have to reposition last minute I will have some backup targets in mind. With the narrow field of view (in my case) I am looking for a tall structure I can get far enough away from to plan for a 62 or so second exposure. I might setup a camera to do star trails depending on where I end up, otherwise in Victoria, I might go 100ASA/f7 62 second exposure (dark frames for noise reduction) I will have to work it out on site. If I find a cool
old barn out in the boonies, I might light it up with some filtered flashlights (foreground object, I’d like to get pro strobes with filters but, hey it’s just a hobby) a bit and make a much longer exposure (trails) as well as a short exposure (2 cameras). I might setup a webcam (VGA) to do video (via dash thru glass),with an SLR lens mounted to it, with slower shutter speeds (I can slow it as low as xxx minutes but, that’s a bit pointless, 1/25th of a second maybe, just whatever works out).I am going to head out and scout for locations at 5pm. I will be in place at least 10-30 minutes before the event depending on the location. An old barn would be nice. I will not step on Private Property without permission regardless of if it’s posted or not. Arriving on scene beforehand I will take some test shots to test focus to make sure everything is in focus and exposure. I will test exposure once just a few minutes beforehand but, the sun will be about 16-17 degrees below horizon at the time of the flare, you just don’t want to setup the camera an hour before hand while it still twilight out.

Positioning

Brightness West/East of Centerline
93.7011 -8 -5.8
93.6611 -7.8 -8.2 – Near Centerpoint
93.6011 -5.8 -8.3
North/South of -93.6611 West should not be a problem the flare should flare slightly sooner as you go South, or slightly later as you go North, but, only a second every x miles. What I do is because the times are not exact is about a minute before the event I look up and start counting to 60 attempting to acquire the Satellites prior to the flare while counting to 60. You don’t want to be looking at the Camera or anything else. I will be moving up or down the centerline checking spots. I will have a laptop, GPS, and internet to do final calculations along with a compass in case I can’t locate the flares based on a star chart.

Checklist

• Make sure you have the position and time of the flares.
• A way of locating the flares (star chart, backup compass)
• Accurate time
• Make sure you setup and take some test shots, test focus, exposure,
  composition. Be sure to check exposure 5 minutes or so before the
  flare, it will still be darkening (but, to a very minimal extent).
• Focus is critical, it’s very difficult to focus in the dark, infinity
  on digital camera’s is no longer infinity, having a foreground object
  makes it so much more difficult. Don’t expect to rely on auto-focus.
• Shutter release
• Maps
• Don’t watch your clock and wait for the exact time of the flare, the
  times are off a few seconds sometimes, about a minute before the flare
  look up and start counting to 60 in your head looking for the
  satellites.
• If it’s windy don’t put a bunch of trees in the foreground.
• Clothing

Star Chart <- click for Star ChartThe flare center is surrounded by finder circles, the iridium’s should be at maximum brightness at the center, starting to flare prior to the circles and ending after the circles. The Iridium’s are flying South to North resulting in a flare starting slightly NE of the finder circles and ending SW of the finder circles. Notable objects nearby. The Alpha star in Ursa Minor is Polaris, all stars will appear to circle clockwise around this star if you want to attempt a star trail shot, in Perseus we have 17P/Holmes just a little to the left and below of the ‘a’ Alpha star in Perseus.

Execution

The Search

I headed to Dairy Queen on Hwy 5 in Victoria to begin my search. I ordered a large pepsi along with a chili dog, no cheese, lots of onions. Then I checked out various area’s of Carver Park Reserve (Three Rivers). The area’s I wanted to shoot from close at sunset. I needed a really tall object or hill (preferably not a tree). I checked out the Lake Auburn Moravian Church, a bit odd looking, too many trees, nice historic landmark, old yet, brick? Like all Three Rivers parks every section is well maintained to perfection. I checked out St. Victoria, nice steeple, well lit at night. The cross on the Steeple was not facing the correct direction (it faced N/S, I needed it W/E or preferably 290/110 degrees), had too many trees around it, and given the time between the flares and exposure time their was too much lighting around the Church. The steeple lighting was very nice. I headed South on 11 all the way to the River, back and forth. The dust from the dirt roads would just kind of linger as if it was just crop dusted for long periods of time (5+ minutes). I settled on the park across the street from St. Victoria. I read the park rules, open until 10:30pm, not a problem.

Composition

Their were no tall objects other than stadium lighting. I had a tree, the problem was that it was too close (depth of field focused on the flares), and wind. It was calm but, a single gust of wind would blow the tree and make it look blurry or out of focus during the 60 second exposure. I had a gust of wind. I took a couple test shots, tree turned out fine, good lighting. Trees are a bit boring oftentimes but, had to have something in the foreground (or might have well packed an EQ-mount and taken a longer exposure). I wanted the flares centered, with the trails of the first satellite going down towards the horizon after the flare, with the trail of the other iridium leading up to the flare. I actually saw the previous iridium pass about 6 minutes prior so I knew the flight path (it didn’t flare, I believe they pass on each plane every 6 minutes or so). I wanted to put Polaris on the left and Perseus, specifically 17P/Holmes on the right. I knew I would have star trails on the right but, might be of some educational value (Earths Rotation around Celestrial Axis). Not a bad shot, if I did it again I might have brought an EQ mount and skipped the tree. The tree also blocked some anoying flood light pointed directly at me.

The Photos

Click on photos to see large versions

Photo – No Labels

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October 27th, 2007 (morning) 17P/Holmes

This evening has clouds comming and going, should be better tommorow. The cloud surrounding the comet’s core/nucleus continues to grow significantly. 5×1s exposures RGB each, Takahashi Epsilon 250 850 mm (f/3.4) ST10-XME.

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October 26th, 2007 (morning) 17P/Holmes

Imaged the comet, hopefully this weekend will be nice and it will be more developed. I had difficulties with this one, it’s soo bright that without some illustrative type wizzardry I can’t get background stars to show up without blowing out the comet so this image has all the levels streched, while I picked up all the background stars they will be too dim to see. Imaged with a Takahashi TOA-150 ST-10XME, 3x exposures 10 seconds each RGB binned 2×2, the Luminosity I am having blooming issues with so it’s an RGB versus and LRGB. It’s going to be really interesting to see how this develops, should be quite the target once it dims and develops a bit more. Given that the tail (if one indeed develops) will be pointed away from the sun with as slight angle parallel to it’s orbit, the Earth is currently between the sun and the comet so the tail will point directly away and slightly off center.

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October 24th, 2007 Comet 17P/Holmes

I received an e-mail from spaceweather.com that Comet 17P/Holmes currently in Perseus had an outburst type event increasing it’s brightness about a million-fold. In the coming days it should be watched for a developing tail or further outbursts. The comet was located immediately visually from within an urban light polluted area under a street light. I took some shots, I will be keeping a separate page here.

17P/Holmes Comet – Outline

17P/Holmes Comet

Canon 350D, 1600ASA, 13 sec, f1.8, Noise Reduction, Levels (poorly)

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