Research Committee Reports & Observations

Double Star Observation

Spectroscopy

Asteriod Hunting Series - Asteroid Astrometry

Asteriod Hunting Series - Asteroid LightCurves

Astronomy Imaging Series - Webcam Imaging

Astronomy Telescope Control

Tuthill Trailer Telescope Restoration

Supernova Hunting Series

More to Come

How can I contribute

Binary Observation

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HJ 2999 - Clif Aschraft Observes A New Star In This Binary System

Email excerpt from Clif Ashcraft

Dated: Saturday, December 02, 2006 09:28:20 AM

Here‘s one of my recent doubles. It‘s HJ 2999, which basically means that it is number 2999 in John Herschel‘s (William‘s son) list of new double stars. It also goes by the identifier WDS 20467+2044 which is how it is listed in the Washington Double Star Catalog. The image below is a stack of twelve of my images taken through three different filters, I, R and V using my ST-8 camera and photometric filter wheel on my 12.5" Newtonian reflector plus a 2x Barlow. I combined the images to form the false color representation shown below where I have mapped I to red, R to green and V to blue in Photoshop. I made this stack just to give a nice image of the multiple star system to go in a paper for the JDSO. The two stars near the left side of the image are field stars included for orientation purposes. The original SBIG images were actually used to make the measurements for the paper with the crosshairs tool in CCDOPS, the software that comes with the camera from SBIG. I also report the magnitude differences between each of the pairs measured on the images obtained through the I, R and V filters.

John Herschel made the original observations of this double in 1831, and two additional measurements were made afterwards, the last being done in 1895, no observations since then. In 1895 the position angle and separation of the AB pair in the system were 221 degrees and 10.3 seconds of arc. Note the significant amount of movement which has happened since then. My observation may allow an orbit to be determined. Note also that the fainter component C was never reported before and will get the designation ACA 6 AC. This means that it is observation number 6 in Clif Ashcraft‘s list of new double stars, and also that HJ 2999 will now be listed as HJ 2999 AB. Kinda neat being John Herschel‘s colleague separated by a few years...

We could do these double star measurements (and discoveries) very easily at Sperry using the 24" and the ST-8 camera and make a valuable contribution to astronomy. Note that the measurement of the orbital period of a binary star provides the only way to actually weigh a star. This is fundamentally critical to all of astrophysics. There are probably no more than 16 individuals worldwide who are engaged in a program of systematic double star observations. The effort is coordinated (and mentored) by Dr. Brian Mason at the US Naval Observatory. Brian also maintains the WDS catalogue and the list of Neglected Double Stars, which is a very good guide to devising an observation program. To find more about the USNO double star resources online, just Google WDS and USNO. There is also an online Journal (JDSO, the Journal of Double Star Observations) dedicated to the publication of our results and an online discussion group for information exchange between observers, catalogers and orbital mechanics.

Spectroscopy

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Spectra of Trapezium by Clif Ashcraft

Email excerpt from Clif Ashcraft

Dated: Feb 2, 2008 12:04 PM

...an image of widened spectra of the trapezium stars taken using the Schupmann as a spectroscope. I may have resolved lines in the visible spectra of the two type B stars (D and B) but not in the type O stars (C and A) , which may be just what we should expect. Spectral lines are weak in type O and could be easily obscured by seeing and insufficient sampling. All of the stars appear to have lines in the NIR region (orange through grey part at the extreme right). Note that the original images were taken at f/14 and I had to use 3x resampling and dithering to bring out the details in the attached spectra. I will redo the experiment at f/30 or so.

Some of the dark lines in the spectrum of star D appear to line up with lines in a comparison solar spectrum, but I can't exclude the possibility that these are chance alignments of stretched noise elements in my spectra. Stay tuned for a better job at a longer focal ratio.

Spectra of Trapezium by Clif Ashcraft

Email excerpt from Clif Ashcraft

Dated: Jan 26, 2008 11:28 AM

I also got a spectrum of the Trapezium at f/14 by tweaking the micrometer screw that tilts the Schupmann field mirror in the east/ west directions. The undispersed image is overlaid to the right of the spectra. Not enough dispersion to see spectral lines and there are sampling artifacts from only working at f/14. I also think that Registax has trouble with the alignment along the direction of the dispersion. The breeze and poor seeing at the altitude of M42 complicated things. Looks cool though. Note the orange and grey streak of near infrared spectrum below the red. I had deliberately left off the NIR blocker for this experiment. There is a blip in the spectral response of the Bayer matrix filter elements (all of them R, G and B) that passes light between 700nm and 1100nm. You can understand the apparent color of the NIR streak by looking at the spectral response of the filters in the plot further down the webpage.

Spectra of Vega Captured by Clif Ashcraft

Email excerpt from Clif Ashcraft

Dated: Saturday, October 28, 2006 12:46:56 PM

The attached is an aligned montage of spectra of Vega taken using a blazed transmission grating placed in the converging beam of my 12.5" reflector. The portions of the spectra taken through the B and V filters to the extreme left are parts of the more highly dispersed the second order spectra. The focal length was amplified to ~178" using a Barlow lens and the imaging was done with my ST-8 camera. The purpose of taking the spectra was to visualize the band pass of the filters I use for photography and double star photometry. The star was allowed to drift unguided to broaden the spectra and make the lines easier to see. Many of the prominent lines in the red part of the spectrum are terrestrial atmospheric oxygen and not part of the spectrum of Vega. The H-alpha line is from the star, not the earth‘s atmosphere.

A critical factor for my double star program was finding the center of the bandpass of my H-alpha filter. One would expect it to be centered about 656.3 nm, the H-alpha line. However, there is always variation in manufacture of interference filters and I needed to know what mine was doing. This was critical for the determination of the focal length of my telescope using the coarse objective grating I had made. Assuming the band center of my H-alpha filter was 656.3 nm, the focal length came out to be 176.71 inches. Knowing that the band center was actually 650 nm from these spectra, I now calculate a focal length of 178.43 inches. This is a significant difference and makes the double star separations I measure from my CCD pictures about one percent smaller than I had been recording in my observations log.

In the lower part of the montage are spectra taken with a more traditional design of spectroscope using collimator and camera lenses and a higher dispersion transmission grating in the parallel light between the lenses. This spectrum also shows that the center of the bandpass of my H-alpha filter is 650 nm. At the bottom of the montage is a spectrum of Vega taken by my friend Jim Daley using an objective prism on his 5" Schmidt camera.

All the spectra are aligned with a published spectrum of photometric filters at the top of the montage to provide a numeric scale.

What‘s Inside - Additional information on spectral measurement - by Clif Ashcraft

This shows all odd orders out to about 33rd order. The spectra are clearly resolved out to about 23rd order. The bottom spectrum is the same as the top one, but with the intensities reduced to show the inner overexposed region with the -1, 0, and +1 orders clearly resolved in the center.

The objective grating is the one I brought in to one of the Friday meetings this summer. A picture is shown below. The slits are one inch apart and the grating fits over the end of my 12.5" Newtonian.

From the spacing of the orders and my determination that the band center of my H-alpha filter was 650.0 nm, I calculate that my focal length is 180.00" in the configuration with the ST-8 camera coupled to the telescope with a nominally 2x Barlow. Note that the Barlow is actually working at 2.4 because the camera focal plane is further back than the focal plane of an eyepiece inserted in the Barlow lens. The focal length will be inserted into the parameters of the CCDOPS program which I use for taking images with the camera and will establish the plate scale for my double star images.

Clif Ashcraft‘s Objective Grating

Asteriod Hunting Series - Asteroid Astrometry

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Image of Comet Pojmanski by Dale Gary

Email excerpt from Dale Gary

Dated: Thursday, March 09, 2006 11:27:08 PM

I took this picture of Pojmanski on Wednesday morning. It is a combine of a number of exposures, shifted to follow the rapidly moving comet, so the stars all make dotted lines. The kind of cyan coloring appears to be correct, since blue and green were about equally bright, and red was quite a bit weaker. The sharply defined tail that you see is the ion tail, but the dust tail is also discernable at about 2 o‘clock.

Image details

The camera is SBIG STL-1301, 1280 x 1024 pixels, 16 um pixel size. The telescope was Meade LX200GPS 10", focal length 2700 mm. The image is an LRGB composite, each filter binned 2x2, with a total exposure 240 s (12 frames of 20 s each) in each filter. The direction and speed of motion (6.9"/min) of the comet were compensated for, causing the stars to appear as a linear series of points.

Asteriod Hunting Series - Asteroid LightCurves

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Contributions from Hank Adams

Email excerpts from Hank Adams to the Research Committee on C/2002Q2

Dated: Mon, 27 Dec 2004 13:05:26 +0000

I believe I forgot to say that the image was obtained at the prime focus off my CG 11. That exposure was for 15 sec. unfiltered 2x2 binning. The longest exposure was for 360 sec. I was unable to detect a tail in any of a series of images. It is likely that the coma is larger than the field of view of the CCD. Comments?

Hank

Dated: Sun, 26 Dec 2004 16:57:31 +0000

On the 22nd I went out to find asteroids. Besides the cold there was an almost full moon and high thin clouds. Well on to plan B, I would image the Moon. It was so bright I completely saturated my CCD; on to plan C. Since Iwas controlling my scope with Guide I looked around to see what else was nearby. I saw comet Machholz nearby. I had tried to see it several days before but it was benaeth my roofline. However it seemed as though I might be able to observe it. I directed the scope toward it. I could see it in my 50mm finder. Then I took several images.

I have appended two images to this email. One is of a 15 second exposure, shiwing a vertical lin thru the brightest picel in the coma. The next is a plot of the brightness along the line. I was surprised to see how steep the values jumped near the center. This plot is linear. Enjoy!

Hank

Contributions from Dr. Dale Gary

Click here for comparison between AIP4WIN and MaximIDL

Email excerpt from Dr. Dale Gary to the Research Committee

Dated: Wed, 10 Nov 2004 16:00:43 +0000

After hearing about the idea to obtain asteroid light curves, I decided to try it last night. I looked the list of suggested asteroids on the Minor Planet Center pages, and selected 539 Pamina, which was in the right part of the sky for me to see between trees, and it was one of the brighter ones at about 13th magnitude. I used my 10" Meade 200LX, and an Apogee Alta camera (512x512 pixels, each of 20x20 micron size). There was only one Tycho-2 star in the field, with listed magnitude 10.82. I attach an image showing that star, a "check" star, and the asteroid. I took about 60 images over a 2h period, and analyzed the photometry with MaxIm DL. I also attach the lightcurve. You can see that the measurement fails near the end of the 2h sequence, which is because the asteroid approaches a faint star that messes up the photometry. But I think you can see! that the "check" star is constant and Pamina is getting slightly brighter. A much longer time sequence is needed to try to see any periodicity. So my conclusion is that this is certainly possible, but it is going to take a long series of data. Of course, one can take bits of data over many days and do epoch folding. The advantage of the Sperry telescope is that we can go much fainter.

Regards,

Dale

Telescope Control

LX200GPS 10 inch and Apogee CCD Camera script control written by Dr. Dale Gary

Email excerpt from Dr. Dale Gary to the Research Committee

Dated: Thu, 2 Dec 2004 03:35:42 +0000

I read the article on hunting asteroids for which Hank had sent the link, and I realized that to do this right would require the ability to point the telescope automatically at many adjacent regions of the sky and control the camera to photograph each one. After looking into it, I wrote the Virtual Basic script listed below, which controls the telescope and camera using the ASCOM platform (http://ascom-standards.org/). The script assumes that the telescope is pointed correctly, reads the RA and Dec from the telescope, and then asks the user how many fields to image, how many frames to take of each field, and how much overlap there should be between fields. It also reads the camera and telescope information and automatically figures out the field of view of the camera. It then moves the telescope in a raster pattern. To test the script, I observed the Orion Nebula on Sunday night, and you can see the result of a 5 x 5 raster of fields here: http://physics.njit.edu/~dgary/astro_images/M42_page.html. The result is pretty amazing (I think). I also took some fields near the ecliptic in the hope of finding a new asteroid, but I haven‘t analyzed the data yet. The data of the asteroid hunt are not that good, because I was still debugging the script. I can demo the script at Monday‘s research meeting if you wish.

Regards,

Dale

Click here to see the code

Click here to see the sample image taken by Dr. Dale Gary using his script

Tuthill Trailer Telescope Restoration

The following link is a Powerpoint (web version) document that Clif Ashcraft presented and discussed in the Feb 19 2005 Research Committee Meeting.

Tuthill Telescope Ray Trace Spot Diagrams for the Tuthill Telescope

Author Clif Ashcraft

The following link is a Powerpoint (web version) document that was presented and discussed in the Jan 29 2005 Research Committee Meeting. The document outlines the project details for performing a feasibility study for restoring the Tuthill Trailer Telescope. The study will develop a recommendation that will be presented to both the AAI and UACNJ Executive Boards for approval prior to execution.

Tuthill Telescope Feasibility Study Presentation

Below is Clif Ashcraft‘s Provisional Sketch of theTuthill Telescope

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Supernova Hunting

Image of a Supernova by an AAI Member Clif Ashcraft

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More to Come

We are busily doing research. COME AND JOIN US!!!

If you‘d like to contribute or participate to the Research Committee please contact Ed Carlos