Friday, October 31, 2008

Few highlights in November - thus the border days count as well

Today and in the following days there are some nice nice line-ups of planets and the Moon in the evening sky, but two of the November highlights, yet another Pleijades occultation and the Leonid meteors, are largely drowned in Moonlight. So, to spice up the list a little bit, Oct. 31 and Dec. 1 are included as well.
  • Oct. 31: Another close encounter with Enceladus for Cassini; the team is again blogging about the experience.

  • Nov. 6: The (first-quarter) Moon only 0.2° from Neptune in the evening (at least as seen from Germany).

  • Nov. 8: Orbit insertion for Chandrayaan 1 after a complicated trajectory to the Moon.

  • Nov. 13: The full Moon occults the Pleijades for Europe - that will be tough to watch, even with binoculars.

  • Nov. 17 (at 1:32 or 0:22 UTC) and perhaps also Nov. 18 (at 21:38 UTC): Two possibilities or just one for 100 Leonid meteors per hour and perhaps even more - but the waning gibbous Moon will interfere heavily.

  • Dec. 1: The Moon occults Venus, for Europe in the late early evening. And Jupiter will be just 2° away.
In other news a fireball as bright as the full Moon was imaged on Oct. 29 over Colorado and has been seen widely (more and more reports). • There is also talk about a moderately fresh impact crater in Alberta, CA. • There will be mutual events of Namaka and Haumea for several more years, thanks to the other moon of the dwarf planet. • Here are comet C/2008 A1 on Oct. 18 and 29P on Oct. 27. • A quickly varying white dwarf, HL Tau 76. • One can watch aurorae on the web - and still Kasatochi stuff in the atmosphere.

• Italian amateur astronomers have imaged Pluto's moon Charon with a 14" telescope. • A really long exposure with a pinhole camera. • The last tracked fragment of "blown-up" satellite USA 193 has reentered on Oct. 9. • There are new features for the World Wide Telescope. • A cool tool lets you rotate the closest stars. • And the activity of the Sun - which was particularly wild 5 years ago and is sometimes connecting with the Earth via FTEs - may be influencing the streamflow of S. America's Parana river, however that might work ...

Sunday, October 26, 2008

Food for thought: weather statistics for the two 2010 solar eclipses out

They are probably the most eagerly awaited websites for the international eclipse chasing (and catching!) community: the detailled weather statitics and analyses Canadian meteorologist Jay Anderson prepares for all upcoming total and annular solar eclipses. Many a tour or expedition has been planned on the basis of these data and graphs - and it won't be different for 2010 when two intriguing eclipses will pass over the Indian and Pacific Oceans, the longest annular one until 3043 and a pretty long total one mainly hitting tiny remote islands. For ASE 2010 the wx stats along the track are stunning, with a deep minimum of cloudiness hardly ever seen in such graphs ... in Birma/Burma/Myanmar which promises up to 95% chances for clear skies! Now they claim to be prepared for visitors, others disagree, and the debate whether to go there has been going on for decades. Runners-up weatherwise (with 80% hope for clear skies) are SW China - and the coast of Kenya, touristically well advanced. For the TSE 2010 it's roughly 50:50 in the Cook Islands, French Polynesia and Easter Island, with Polynesia somewhat ahead at 55% clear skies (but hardly any solid ground, only remote atolls); South America - at sunset - has prospects far worse.

In other news it took a while for the Orionids profile to stabilize; now a peak of these meteors around midnight Oct. 20 with a ZHR just below 40 seems likely. How the Orionids fared night after night can be seen in reports of Oct. 20, Oct. 21, Oct. 22, Oct. 23, Oct. 24, Oct. 25 and Oct. 26. • Videos of a Canadian fireball are being hailed as rare. • There is a nice resource on 2008 TC3 and its impact, esp. an analysis of the astrometric effort and an attempt on periodicities in the lightcurve. Elsewhere TC3's discoverer speaks on what it all means. • There is an unusual list of all potentially hazardous asteroids - for all terrestrial planets. • Following TC3 there were more close calls, e.g. by 2008 US. • And 2008 TT26 came within 3.5 lunar distances: a preview, another and more pictures - and a very periodic light curve with a 7 hr period. • Oh, and there apparently another megacryometeor incident, making headlines.

• It's now one year since comet Holmes brightened dramatically - yet checking the technical literature, there has shockingly little science come out of this breathtaking sky event (which was easily visible to the naked eye), including only about 3 attempts to understand what happened. • Meanwhile the current outburst of 29P is winding down. • Plus Rosetta-target 67P on Oct. 21 and Oct. 20. • Amateur astronomers played a role in recovering XMM-Newton after comm trouble. • NASA explains how the ATV reentry was observed. • A paper describes MCAO hi-res NIR imaging of Jupiter. • A Spanish press release with nice galaxy images comes with a detailled explanation of the image processing. • And light pollution recently got a lot of press (here is the Nat'l Geographic package) - and has become a topic even in Hong Kong.

Monday, October 20, 2008

Orionids perform well, despite Moon interference

European reports from the night Oct. 19/20 speak of a fine performance of the Orionid meteors in spite of lunar interference this year. The meteor rate already exceeds 40/hour (under assumed perfect viewing conditions), and the peak is expected only in the coming night. • Meanwhile a new analysis of the Leonids predicts a max. rate of 150 this year. • A detailled interview (ca. 10 min. MP3) on the Jodrell Bank meteor system, with more background here. • A few more details of the 2008 TC3 bolide observations by a secret satellite - and also more on the indirect webcam observation: Reference observations near fullmoon show nothing, so the airburst must have been much brighter, even from 700+ km away!

In other news a dwarf nova is in outburst for the 1st time since 1997, but only at 12 mag. • A supernova extinction record: 16 magnitudes! • The physics of the Deep Impact impact are still mysterious. • The discovery of comet Cardinal in Canada - which doesn't look like much - is spawning a press release ("only the second Canadian discovery of a comet, using a Canadian telescope, in nearly a decade") and news and blog coverage in the country. • Comet Tuttle is binary. • And the HST has observed Pallas, an asteroid of which one hears little.

• A big prominence was seen on the Sun where STEREO imaged another one on Sep. 29. • Analysis of a flash spectrum obtained during the Aug. 1 eclipse - about which some 40 pages appear in TOTALITY! #8. • The German parliament held a hearing on light pollution with mixed responses. • Unusual radio images of our Moon can be seen here (under "ALMA Project News" as Fig. 5) - for comparision, the Moon at many other wavelengths. • Metals have been detected in NLCs, a possible clue to their formation. • And one should go to Canada for the best aurora views.

Monday, October 13, 2008

"McNeil's Nebula" shining in old glory again!

Already on Sep. 1, The Astronomer Electronic Circular #2478 had reported an "apparent brightening of V1647 Ori and its associated (McNeil's) nebula to mag about 16.7 on an unfiltered CCD image taken on Aug. 26.789 UT with a 0.60-m f/5.7 reflector," while "neither the variable star nor the associated nebula were visible" in January with a limiting mag. of 17.5. Now a picture of Oct. 12 shows the famous nebula practically as bright as in 2004 during its famous appearance out if nowhere (and discovery by an amateur astronomer). Observations followed in many wavelengths and a lot of papers were written e.g. about the bright state and the subsequent fading - now more can be learned about the eruptive variable star V1647 Orionis behind the show.

In other news a new bipolar active region on the Sun (#1005) on Oct. 12 - and 21 hi-res pictures of the Sun at various wavelengths. • New Keck pictures of Uranus and its clouds and rings, yielding clues to that planet's seasons. • Comet 29P on Oct. 12 and Oct. 10 and 51P on Oct. 12 and Oct. 10.

• The webcam images of the predicted bolide are back, together with some geometry. • We are still learning about the deep impact made by Deep Impact - and we will make the next one (on the Moon) next summer or fall with LCROSS.

• A planets conference at Cornell is being archived well. • Taking the fight against light pollution to parliament in Germany. • And remarkable pics of a plane in front of the Moon ...

Friday, October 10, 2008

Another "lost" comet recovered after over 100 years!

"Nearly a month ago two Japanese amateur astronomers re-discovered Comet Giacobini which had been lost for 111 years [see the 2nd paragraph here]. Now this weekend comes word that an object found by professional astronomer Andrea Boattini of the Catalina Sky Survey is also a re-discovery of a long-lost comet," reports Carl Hergenrother: "After Boattini’s find was officially announced, Maik Meyer of Limburg, Germany suggested that this comet was actually the same as a comet last seen on 1892 Dec 8." So it's now comet P/2008 T3 (Barnard-Boattini) though it will become 206P/Barnard-Boattini in a few weeks. The original discovery was a milestone in the history of astronomy as it constitutes the first one using photography.

In other news more images of comet 29P in outburst of Oct. 9, Oct. 8 (more, more) and Oct. 7, also comet 51P on Oct. 6. • More details of the MeteoSat bolide observations have become available. • The solar corona during the TSEs of 1994 and 2008 was extremely similar (an interesting observation, given the strange changes in the solar wind since). • Another report from the Herzberg star pary. • From Oct. 11 to 15 many talks from the DPS Meeting, a major planetary sciences conference, can be followed online. • And this blog has now also Twitter channel ...

Wednesday, October 8, 2008

QUICK UPDATE: More detections of the predicted bolide - from space and by webcam

There is now a Meteosat image of the airburst over Sudan which "was visible in all 12 of the satellite's spectral channels, covering wavelengths from 0.5 to 14 microns" - and a webcam in Egypt showed how the ground was illuminated by the fairly distant explosion low on the horizon. (A website with screenshots is currently down.) Plus there is a cryptic notice by JPL about direct observations of the airburst that may refer to data from an early warning satellite (those are regularly detecting such bursts but rarely are the actual measurements shown).

The case of 2008 TC3 is now being analyzed widely: What if this had been a bigger body which would have impacted the ground? This blog has already learned of a plan to set up an "official" website where the whole world can be watching how the impact probability ellipse on Earth will shrink and move as more astrometry comes in (and the response by observers this time has been huge). More video clips in sunlight are here, here and here: Some show a variation in brightness that may reveal the state of rotation of 2008 TC3 just hours before its demise.

Tuesday, October 7, 2008

Predicted airburst detected via infrasound; possible sighting from plane, via seismic signal

So far no report has come in from someone observing the airburst from the ground, no wonder given the remoteness of the area, but a few other detections have come in: an infrasound detection system in Kenya has seen a signal many minutes later that matches expectations very well, the crew of a distant airplane saw a flash at the right time - and there may even be a faint seismic signal, caused by the airwave coupling into the ground. There are also observations of the asteroid entering Earth's shadow, its rising brightness while approaching Earth and a video clip of its motion in the sky. New links are added here all the time.

In other news images of comet 29P on the 6th and of all terrestrial planets on Sep. 20. • A detailled report from the 9. Herzberger Teleskoptreffen. • A new service for astronomical weather predictions for the whole planet. • And a New York Times editorial on light pollution.

Monday, October 6, 2008

STOP PRESS: Mini-asteroid to burn up over Sudan tonight!

"This is a first," David Morrison just wrote in his NEO News: "a very small asteroid (or rock) has been discovered that is on course for an impact tonight in Sudan. This information is from various reports posted to the Minor Planet Mailing List [the first message there being this; DF]. The impactor is only about 2 m across and will break up in the atmosphere, with no risk to those on the ground. (If something this size hit in the daytime, it would probably not be noticed, but at night it should put on quite show). Alan Harris writes that this object, with the survey-assigned designation 8TA9D69 [and the current designation 2008 TC3; DF], was discovered by the University of Arizona Mt. Lemmon survey and will almost certainly, tonight, become the first impacting bolide discovered before entry into the Earth's atmosphere. Steve Chesley (JPL) reports that atmospheric entry will occur on 2008 Oct 07 0246 UTC over northern Sudan.

Andrea Milani of the University of Pisa wrote the following: Today the object with the provisional designation 8TA9D69 was submitted to impact monitoring by using the normal software of the NEODyS system, by using the observations as reported by the MPC on the NEO Confirmation Page. Based on 26 optical observations from 2008/10/06.278 to 2008/10/06, the probability of impact is between 99.8% and 100%; in practice the impact can be considered sure and is for tonight. Our computation has already been confirmed independently by others, including the JPL NEO Program Office (with which we consult in all relevant cases of possible impact). The effect of this atmospheric impact will be the release, in either a single shot or maybe a sequence of explosions, of about 1 kiloton of energy. This means that the damage on the ground is expected to be zero.

The location of these explosions is not easy to predict due to the atmospheric braking effects. The only concern is that they might be interpreted as something else, that is man-made explosions. Thus in this case, the earlier the public worldwide is aware that this is a natural phenomenon, which involves no risk, the better. This is the first time an asteroid impact has been predicted, and it reflects the increasing capability of the Spaceguard Survey. There was one previous false alarm when, for a few hours around Christmas 2004, it appeared that an impact by a 30-m asteroid was possible, but this was ruled out by additional observations. The current case, however, seems much more solid." There are also a CfA Press Release on the impending airburst, numerous MPECs, this one being the first and this one the most recent, and a note from Switzerland.

Sunday, October 5, 2008

MESSENGER's 2nd Mercury fly-by - in a few hours - highlight of this month

With few celestial highlights, this month will probably be dominated by space events - and while normally launches are not listed here for good reason, given frequent delays (just witness the sudden slip of the HST SM4!), exceptions are in order since since the four science spacecraft on the launch pads or approaching those are pretty unique. The first event is inevitable:In other news dwarf planet king Mike Brown is no longer hunting, but there could be a few more large bodies out there. • A rare image of comet 17P/Holmes of October 2! • The recent outburst of comet 29P has triggered lots of observations: Here are a crude light curve and views of Oct. 4, Sep. 29 and Sep. 28. • 2007 N3 and 205P on Oct. 2, a new Boattini and yet another one, with low excentricity. Plus many comets on Oct 4. • Is this the sharpest ground-based Jupiter, with high-end adaptive optics in the NIR? Compare this to, e.g. these or these amateur images of Jupiter with a vastly smaller scope. Plus motions of the Jovian moons.

• The now-famous wide-angle image of the Aug 1. TSE also shows a faint distant Coronal Mass Ejection (clarified in the caption). There are also a new super-high resolution image (detail) and a view from a different location (also with higher magnification). • While another activity region has appeared on the Sun, a NASA story on the current minimum has caused widespread confusion (see also here, here and here) - using the statistical method described here would have avoided the troublesome 'spotfree' definition issue. Meanwhile a cool prominence was seen - and RHESSI data show minute variations in the Sun's oblateness with the cycle.

• There is a faint nova in Aquila, R CrB remains at 14.5 mag. in a long minimum, and Kasatochi's effects are still there now & then. • Here is a cool video of the ATV's reentry of which also some stills exist. The trash transporter was imaged in hi-res on Sep. 27 (another view), while the ISS & a Progress were caught on Sep. 25. • Finally some impressions from Mauna Kea - and the whole Universe in one cartoon, logarithmically ...