07/02/06

FRANCISQUITO MAKES RARE DOUBLE DISCOVERY!

After taking literally thousands of images of the night sky, it was inevitable that a yet-to-be-discovered minor planet would drift into the field of view of one of Francisquito's telescopes.  And sure enough, it happened on the evening of August 10th, 2004 while making routine astrometric observations of recently discovered Near Earth Asteroid 2004PM2 (Francisquito had also assisted in the 2004PM2 discovery).  But even more remarkable was the rare chain of discoveries that began on that night.

It happened like this.  After processing the 2004PM2 images in a way that enables positions to be measured for faint, fast-moving objects, the images were re-processed in order to look for very faint (down to magnitude 20), slow-moving objects.  This is standard procedure at Francisquito, and is done specifically to look for undiscovered minor planets such as asteroids and comets.  The fact is that Francisquito does very little searching for potential new discoveries (i.e. scanning the sky without aiming for a specific object), but we are always looking for new discoveries in each image we take.  In the August 10th, 2004 re-processed images for 2004PM2, a faint, fuzzy blob was noted moving from frame to frame in the far upper-right corner of the images.  A quick check with a recently downloaded catalogue of asteroids and comets showed no known object at that particular location.  Some crude position measurements were made for the fuzzy blobs and run through an on-line catalogue/object checker provided by the Smithsonian Astrophysical Observatory's Minor Planet Center (SAO/MPC, or MPC for short).  Again, nothing came up in that area, or even close by.  Things started to look interesting.  Through a tedious but effective procedure which we at Francisquito call Iterative Signal Condensation (ISC), an on-line tool provided by the MPC (called the New Object Ephemeris Generator) was used to help re-process the images in a way that turned the fuzzy blobs into sharply focused points of light.  The object was then given the temporary designation "FSQ005" (Francisquito had identified at least 4 other discovery candidates before this particular one, which did not materialize into discoveries for various reasons).  Once the object was sharply focused, precise position measurements could be made.  With these precise measurements, the New Object Ephemeris Generator was also used to make limited predictions of the object's position for a few days into the future.

In order to get credit for a discovery, a potential new object must be observed on at least two successive nights, ideally on nights close together.  Fortunately, the fine Southern California weather continued to hold and confirmation observations were programmed for the evening of August 11th, 2004.  When the images were examined in the wee hours of the morning, the discovery candidate was seen moving brightly through the center of the image set.  Eureka!  Position measurements were made for this set of images as well.  Then, per Francisquito's standard procedure, all parts of the FSQ005 images were carefully re-examined for moving objects.  And there...moving in the extreme lower, right-hand corner of each image was another series of fuzzy blobs, though noticeably fainter than the blobs seen the night before for object FSQ005.  Again, two exhaustive catalogue checks were performed for this latest object, and again, nothing showed up at its location.  Was this possible?....two potential discoveries on two successive nights?  The ISC procedure was used to turn the second set of fuzzy blobs into focused points of light, and the object was given the temporary designation FSQ006. 

The two nights of position measurements for object FSQ005 were flagged as pertaining to a potential discovery and sent to the MPC early in the day on August 11th.  By the end of the day the MPC had acknowledged an official discovery and issued the provisional designation 2004PC27 for this object.

An animated series showing the discovery images for minor planet 2004PC27 can be found at this link.  Dial-up Internet users should be aware that this animation is about 425KB in size, so please be patient as it downloads.

Then, it was on to FSQ006!  Second-night observations were programmed for August 12th, and happily it showed up where expected, moving in a smooth arc across the center of the images. The two nights of position measurements for FSQ006 were also flagged as belonging to a potential discovery, and sent to the MPC early in the day on August 12th.  By the end of the day another discovery was acknowledged, this time being given the provisional designation 2004PX42.

So, one might ask, how significant are these discoveries?  Well, minor planets 2004PC27 and 2004PX42 are categorized as Main Belt Asteroids.  They orbit the Sun in about 3-1/2 years, sandwiched between the orbits of Mars and Jupiter.  There are literally thousands of Main Belt asteroids; at best, these discoveries will add a little more to our understanding of the distribution of matter in the solar system.  Main Belt asteroids pose little if any danger to us on Earth, unlike Near Earth Asteroids and Earth-approaching comets.

Here are some interesting physical facts regarding minor planets 2004PC27 and 2004PX42.  They are estimated to be about 1km to 3km in diameter, and were each discovered at a distance of about 175 million km (105 million miles) from Earth.  They were discovered shortly before their next astronomical "opposition", meaning they will continue to brighten until they are more or less aligned with the Sun and Earth.  After reaching opposition, they will become fainter and fainter until they are not be detectable with Francisquito's instruments, after which they will be hidden in the glare behind the Sun.  It is expected that both 2004PC27 and 2004PX42 will be observable by Francisquito in their current opposition period until late November/early December 2004.  The orbital motions of the Earth and these minor planets will interplay in interesting ways over the coming years.  They will become visible periodically, at intervals of anywhere from 18 months to four years.  During some of the coming oppositions they will be too faint to detect with a 30cm telescope like Francisquito's, but at other times they can be observed (and measured) by Francisquito again. 

Additional details on the 2004PC27 and 2004PX42 discoveries (including the original discovery images) can be found by following a link on this web site's "Observations" page, or by following this link directly.