These images show the complex coma around comet 174P/Echeclus = (60558). This object was orignally classified as a Centaur. Choi and Weissman (IAUC 8656) reported a coma around this object in late 2005. We had imaged this object in 2004 and found no coma.
These images were obtained April 2.3 UT, by Steve Tegler and Guy Consolmagno using the 1.8 meter Vatican Advanced Technology Telescope on Mt Graham, AZ, and processed by W. Romanishin. Each rectangle covers an area on the sky 285 by 195 arcsec. This image is a shifted and averaged combination of 2 exposures through an R filter, each of 180 second exposure time.
The top rectangle shows the nucleus and high surface brightness extended feature to the west (right) of the nucleus. The bottom image, a smoothed and rewindowed version of the upper image, emphasizes the much larger low surface brightness coma around this object. The extended object can be traced for over 2 arcmin in diameter.
Note in particular that the nucleus is clearly separated from the peak of the high surface brightness extended region to the west (right on image) of the nucleus. This suggests that the coma was produced by a transient event, and that the nucleus and coma are now somewhat spatially separated. Perhaps we are seeing the result of a collision of this object with a smaller one? A natural "Deep Impact"??
At present, this object is almost 13 AU from the Sun. The nucleus has an R magnitude of 20.1. The entire extended structure has an R mag of about 16. The higher surface brightness condensation to the west has an R magnitude of about 18.
This "clear sky clock" gives information about astronomical observing conditions predicted over the next 2 days for Oklahoma City area. To understand what is being displayed, click on green "click for help" and read the extensive help info. Then click on the small box labeled "Explain color and details when you mouse-over" in the pink box labeled "Image Control" on the left side of the help page. Enjoy!
This is the home page of the University of Oklahoma (OU) astronomical Observatory. Info on the educational and research activities of the OU Physics and Astronomy Department can be found here. General info on the University of Oklahoma can be found here.
William Romanishin - - - wjr AT nhn DoT ou doT edu
The OU Observatory. In the background is the Oklahoma Memorial Stadium. See bottom of page for a picture of our telescope.
The binary KBO 2000 CF105 was discovered by Noll etal (IAU Circ. 7857) using the Hubble Space Telescope in January of 2002. The images of 2000 CF105 below were obtained by W. Romanishin and S. Tegler in April 2002 using the Keck telescope on Mauna Kea with 0.7 arcsec seeing. The images are in the R band, and are a sum of 4 images each 10 minutes exposure. For the summed image of the KBO pair, the indivdual frames were shifted to account for the motion of the KBO between the different exposures. The KBO moves during each exposure, of course, resulting in a slight trailing of each individual image. At the time we observed CF105, the object was barely moving with respect to the background stars (about 0.3 arcsec per hour), so that the "trailing" during each 10 minute exposure was an almost imperceptible 0.05 arcsec. North is to the top and east to the left. Each square image is a small portion of the entire CCD image, and is about 8 arcsec on a side. The images (left to right) are: (1) the observed image of 2000 CF105; (2) the observed image with the primary (brighter) component of the binary removed; (3) the observed image with the secondary (fainter) component removed; (4) the observed image with both components removed; and (5) a star on the same summed frame, used to derive the PSF (point spread function).
A preliminary report on the the research reported here has been published by Romanishin etal (IAU Circ. 7962)
The preliminary numbers derived from these images are: the two KBOs are sepearated by 0.8 +- 0.2 arcsec at a position angle of 103 +-5 degrees. The brighter KBO is 0.6 +- 0.2 mag brighter than the fainter. These numbers are about the same as those deived from the discovery HST images taken about 3 months earlier.
To derive the images with components subtracted, a star in the field (the PSF star) was used to model the shape of the image of each individual KBO. The PSF star image was shifted, scaled in intensity, and subtracted from the observed image until the KBO image "disappeared". So far, only a trial and error process of changing star center and intensity has been carried out, leading to the images below. A more systematic fit is in progress. We also have blue band images of the object, and comparison of the blue and red images should give us some information on the colors of the individual KBOs.
Contact info for miscellaneous space- related programs and places in the Great State of Oklahoma. Some are related to universities, some aren't. If you know of something that should be here, send me an email (wjr@nhn.ou.edu). Click here.
Links to web pages and other contacts for resources of interest to a wide range of folk. Click here.
I am trying to organize amateur astronomers who have access to suitable telescopes and CCD cameras in a project to provide longterm monitoring of the brightnesses of Centaurs. Centaurs are objects that orbit in the outer solar system. Although they have been called "minor planets", they may well be more like comet nuclei (icy bodies) than asteroids (rocky/ metallic bodies). They probably undergo outbursts and brightnenings that should be followed.
I gave a talk on this topic at the recent (May 2001) MPAPW (Minor Planet Amateur Professional Workshop) meeting in Tucson. A pdf version of my paper can be found here. This paper has a list of bright Centaurs and when they should be observable. If you are interested in this project, try to image one or two of these objects and email me- I will have more details on this page by end of summer.
We have compiled plots for many centaurs which include magnitudes, distance from the sun, declinations, and elongations. It's useful stuff to look at if you plan to observe any of these objects. Click here.
Here is an additional page for scattered-disk objects. This page also includes 3 panel and 4 panel plots, similar to those found on the above centaur page. Click here.
The number of outer solar system objects contniues to grow at a fast pace. Many of these objects are so faint as to be beyond the reach of all but the largest telescopes, but some are bright enough to be observable with more modest equipment. I have made some lists of outer solar system objects SORTED BY MAGNITUDE- so you can quickly tell if there are any objects bright enough to study with your equipment. I hope to update these lists every month, when the MPEC entitled "DISTANT MINOR PLANETS" is released. Click here.
As better-defined orbits become available, objects are assigned official numbers by the Minor Planet Center. Also, the MPC assigns names to some objects. Thus, what these objects are called changes with time- first an object is known by its year and designation (e.g. 1995 GO), then later it might be assigned a number (1995 GO = 8405) and then maybe later a name (1995 GO = 8405 = Asbolus). To try to keep track of all these (Asbolus will always be 1995 GO to me!) here is a list of objects with numbers and names and their original designation. Here is a list of IAU observatory codes for observatories that have submitted astrometry of KBO/Centaurs to th MPC (list is not complete!)
I am writing a "textbook" aimed at anyone who wishes to do astronomical photometry with CCDs. This book is used in the course I teach each fall, ASTR 2513 "Observatory Methods". For more info on the book or course, click here.
The OU 0.4 meter Meade LX 200 telescope. On top of the main tube is the guide telescope, a 3.5 inch Questar feeding an SBIG ST8 CCD camera. The big CCD chip in the ST8 is used for guiding, allowing a wide field from which to chose guide stars. The main telescopes has an Optec filter slider, a JMI focuser, and a AP7p CCD camera.
