November 2007 - Utah-Astronomy - mailman.xmission.com

Lunar occultation of Pleaides obs op 11-24 beg 4:40am
by Kurt Fisher 19 Nov '07

19 Nov '07

Not having done any lunar occultation observing before, I decided take a stab at planning for the lunar occultation of 19 Tau and 16 Tau in the Pleaides on Thanksgiving weekend - Nov. 24 beginning at 4:40am. The occultation of the Pleaides by the Moon will also provide a good asthetic astrophotography opportunity. Details, including charts, can be found in the Utah astro wiki at - http://www.utahastronomy.com/Current_observing_events#Nov._24_beg_4:40_am_L… or just look at the index at the top of - http://www.utahastronomy.com/Current_observing_events and click on the Nov. 24 entry. Patrick, any experienced based comments and help on how to observe this event would be appreciated. I am concentrating on detecting the separation of the components of 19 Tau (0.01" at limits of detection by this method) and 16 Tau (0.1" an easier learning target). From a point 29km southwest of Salt Lake, there appears to be an opportunity to observe a lunar graze by a component of 16 Tau. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Re: [Utah-astronomy] A 3D construction of Comet 17P
by Kurt Fisher 19 Nov '07

19 Nov '07

It would appear the situation has changed since 11-10 and my 11-10 based 3D construction. The tail light spot trailing the comet may now be showing a position angle off to one side of the medial center line of the comet. Amateur images published on the web through 11-11 were showing the disconnected tail about 34-35' behind the center of the coma, but at a line directly trailing the medial line of the coma and central condensation. A great triptych by John Wunderlin posted on Cloudy Nights and Spaceweather.com illustrates the situation on 11-10. http://spaceweather.com/comets/holmes/10nov07/John-Wunderlin1.jpg Based on the assumption that the position angle of the dust light spot trailing the comet on 11-10 was nearly on the sun-comet line, I prepared the 3D construction above. This assumption was questionable, because comet dust tails typically curve away from the comet, e.g as seen in comets McNaught in 2007 and Hale-Bopp in 1997 - http://en.wikipedia.org/wiki/Image:Comet_P1_McNaught02_-_23-01-07.jpg http://en.wikipedia.org/wiki/Image:Comet_Hale-Bopp.jpg An early 10-26 image and report by the professional astronomer Dr. Pierre Bastien of the Universite de Montreal suggested the then nascent tail may have been at an angle. See - http://www.spaceref.com/news/viewpr.html?pid=23901 As the tail grew, the did not appear to be any deviation in position angle of the tail relative the medial line of the comet, as shown in the amateur images above. But the 11-15 wide-field image posted on Cloudy Nights by "Hiro" may show a changed geometry. http://farm3.static.flickr.com/2100/2040106475_4557f789e6.jpg The light spot trailing the comet - now about 60' behind the comet - in "Hiro"'s 11-15 image appears to be slightly off-center from the medial line of the comet. This would be consistent with a far end of the disconnected tail drifting into a curved shape. Subsequent images may clarify if there is a trend. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Re: [Utah-astronomy] Mosiac problem solved! See reprocessed comet view
by Kurt Fisher 18 Nov '07

18 Nov '07

Congrats, Joe, lookin' good. http://gallery.utahastronomy.com/v/Joeb/Holmes.jpg.html Now try the Rotational Gradient tool - http://www.cyanogen.com/help/maximdl/Rotational_Gradient.htm or the Rank Filter (radius 7, width 0.5) to try and bring out some detail in the central condensation. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Comet 8P Tuttle - co-object astrophoto opportunities
by Kurt Fisher 18 Nov '07

18 Nov '07

I have assembled a chart and table concerning next months comet - Comet 8P Tuttle at the utah astro wiki - http://www.utahastronomy.com/Current_observing_events#8P_co-object_photo_ops As Comet 8P loops through Cass, And, Tri and Psc from mid-December to maximum brightness in the first week of January 2008, the comet will pass a number of other objects - creating opportunities for take dramatic astrophotos. Unlike November's Comet 17P, Comet 8P will present with a Sun-Target-Observer angle between 47 and 70 degrees. (Comet 17P presented as only 12.9 degs.) Earth observers will be well-placed to see any tail, if it forms. I have also stubbed-out a general Comet 8P entry with background links and info - http://www.utahastronomy.com/Current_observing_events#Comet_8P_Tuttle_12-14… Wikis are intended to be a joint-authoring environment. Please feel free to edit and add as you desire. - Happy imaging - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Misc obs rep: Leonids
by Kurt Fisher 18 Nov '07

18 Nov '07

Took a 1/2 hour at 5:45am to 6:15am (with the morning cup of java) from downtown SLC, UT to watch for Leonid meteors. The NASA meteor Fluxtimator ( http://leonid.arc.nasa.gov/estimator.html ) predicted a zhr of 2.9 at that time (well-past the maximum shower peak 10 hours prior to that time). Saw two mag 2 streaks during that time period. The velocity of the Leonids are about 71kms - compared to 59kms for the Persids earlier this year. The two streaks were bright defined lines lasting less than 1 sec with progressively grey-yellow-white colors. The slower Persids (that were observed at a more grazing off-zenith angle) had a white color with long-smokey tails. Brighter Persid meteors generally had tails that were visible between 1 and 2 secs. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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M-33
by Patrick Wiggins 18 Nov '07

18 Nov '07

Got this 9 panel mosaic of most of M-33 this morning between asteroid searches: http://gallery.utahastronomy.com/v/patrickw/M33.JPG.html pw

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A 3D construction of Comet 17P
by Kurt Fisher 16 Nov '07

16 Nov '07

Because Comet 17P presents at a high Sun-Comet-Observer angle (approx. 78 degs), its physical structure is more difficult to appreciate. A 3D construction of the comet and its tail was attempted to better understand what is seen in the eyepiece. Using ephemeris data on the Sun-Comet-Earth and Sun-Earth-Comet angles and distances and a 2007-11-10 image by Thorsten Boeckel on CloudyNights and spaceweather.com, I have prepared a speculative 3D construction of Comet 17P on that date. The constructed model is dependent on the weak assumption that the tail extends back from the comet roughly in a straight line along the Sun-Comet vector. Thorsten Boeckel's original image can be viewed at: http://spaceweather.com/comets/holmes/10nov07/Thorsten-Boeckel1.jpg Computed physical parameters from the construction for 17P on 2007-11-10 are: Distance to comet - 1.622 a.u. Coma diameter - 23' - 1,623,405 km Outer halo diameter - 46' - 3,246,738 km Distance of near tail spot on Boeckel image - 34.5' - 12,379,417 km Distance to end of tail tip from center of coma - 57.5' - 19,577,970 km Diameter of tail end - 46' - 3,508,700 km The resulting construction looks similar to the Boeckel image: http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/040.jp… http://gallery.utahastronomy.com/d/10715-2/040.jpg but unlike the real object, the model can be rotated in 3D: http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/041.jp… http://gallery.utahastronomy.com/d/10718-2/041.jpg A self-loading VRML plug-in of the 3D construction can be found at: http://members.csolutions.net/fisherka/astronote/observed/C17P2007/Comet17P… or the raw VRML wrl file can be downloaded directly from: http://members.csolutions.net/fisherka/astronote/observed/C17P2007/Comet17P… for use with other VRML browswer plug-ins. Leveraging ephemeris data from the NASA-JPL Horizon online applet, I obtained the Sun-Observer-Target(comet) and Sun-Target-Observer angles and distances for the date of Boeckel's image. This simplified reduction of a 3D reconstruction of Comet 17P to plane trigonometry. The urls listed in the Addendum to this note illustrate the process used to solve various Sun-Comet-Earth plane triangles to arrive at an estimate of the length of the tail of Comet 17P. The resulting construction was used to build a 3D model of the comet using VRML 2.0. Although a speculative model that is probably not accurate, it is hoped that this 3D construction of 17P and its tail will help amateurs to better understand what is seen in the eyepiece. This is an amateur attempt at 3D construction, so any corrections and criticisms are welcomed and appreciated. - Kurt Addendum - Links to plane trigonometry construction panes http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/030.pn… http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/031.pn… http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/032.pn… http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/033.pn… http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/034.pn… http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/035.pn… http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/035A.P… _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Re: [Utah-astronomy] Is a puzzlement (Was: 17P - 11-16-2007 10UT - Misc)
by Kurt Fisher 16 Nov '07

16 Nov '07

Joe asked: > That's really nice, Kurt. My question is, why is the > coma roughly spherical if it's shooting away from some vent? > Thanks, Joe I don't know, Joe. Speculating, like most explosions, I suspect that there is a differential energy flux from the center to the outside of the event. For example, lunar craters have two halos - the bright Copernician rays represent the high energy ejecta from the initial impact. Crater Copernicus's smaller dark halo represents the eject from the end of the event - where most of the energy of the impact is exponential dissipated. In comets you have the highest-energy ion tail being ejected out the tail, the next lower energy dust tail exiting in a curve. In the coma of 17P we see the higher energy streamers and central condensation being ejected in a linear oval out of the back of pseudo-nucleus. The spherical shell may represent the lower energy dust particles at the edges of the eruption that do not have enough energy to achieve escape velocity from the weak gravity field of the comet. But again, I'm guessing. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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17P - 11-16-2007 10UT - Misc
by Kurt Fisher 16 Nov '07

16 Nov '07

Holmes images from this morning 11-16-2007 10UT. 2 deg http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/036.jp… 1.5 deg http://gallery.utahastronomy.com/v/kurt/solarsystem/Comet+17P+Holmes/037.jp… Telephoto lens coupled to Meade DSI Pro I. 4 sec x 8 and 15 stacked. Temperature in valley was freezing - breath visible and frost on cars. At Little Mtn pass, it was a comfortable 6 deg C. Little pollution very low for that location. Sky brightness 20.17 MPSAS. M36 and M38 at zenith naked-eye objects. Holmes spetacular but dimming in small refractor. Small dim, detached pseudo-nucleus seen in the 1.5 deg image here also seen visually at U of U star party Wednesday night in LX200 at high mag. - Kurt _______________________________________________ Sent via CSolutions - http://www.csolutions.net

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Re: [Utah-astronomy] Friday Nov. 16 Star Party in Lindon rescheduled for 14 Dec.
by Richard Tenney 16 Nov '07

16 Nov '07

The decision was made to scrub tonight and reschedule for 14 December. Sorry for the late notice, and thanks to those that have volunteered to help. Rich --- Chris Russell <chris(a)therussells.net> wrote: > > > Rich, has a decision been made on whether this is > going to take place? > > I just wanted to make sure in case I missed an > email. > > Thanks. > > ----- Original Message ----- > From: "Richard Tenney" <retenney(a)yahoo.com> > To: "UVAA" <uvaa(a)mailman.xmission.com>, > "Utah-Astronomy" > <utah-astronomy(a)mailman.xmission.com> > Sent: Thursday, November 15, 2007 11:25:15 AM > (GMT-0700) America/Denver > Subject: [Utah-astronomy] Friday Nov. 16 Star Party > in Lindon reminder > > Just a reminder about tomorrow night's star party at > > Timpanogos Academy (Middle School) in Lindon (55 S. > 100 East). Because the weather forecast is iffy, > the > go / no-go decision will be tomorrow morning. I > will > let you know then if we are on, or if they will > reschedule for Dec. 14. > > Thanks, > Rich > > > > > ____________________________________________________________________________________ > > Get easy, one-click access to your favorites. > Make Yahoo! your homepage. > http://www.yahoo.com/r/hs > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > > Visit the Photo Gallery: > http://gallery.utahastronomy.com > Visit the Wiki: http://www.utahastronomy.com > ____________________________________________________________________________________ Be a better sports nut! Let your teams follow you with Yahoo Mobile. Try it now. http://mobile.yahoo.com/sports;_ylt=At9_qDKvtAbMuh1G1SQtBI7ntAcJ

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