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The
TIE User's Guide and Workbook
for Scholastic Programs and Amateur Studies
Copyright 1997 TIE Project
Version 2.1
Prepared
and Edited by
Blake Bartosh
Barrett Duff
TIE
Project Sponsored by
Mount Wilson Institute
Jet Propulsion Laboratory
National Aeronautics and Space Administration
TIE USER'S GUIDE
The 24" Telescope and Equipment
The TIE Project currently utilizes a scientific-grade 24-inch reflecting telescope, with a focal ratio of f/3.5 and a focal length of 84 inches.
The telescope is located at the Mount Wilson Observatory complex, overlooking the Los Angeles basin in the San Gabriel Mountains of Southern California, at an altitude of 5635 feet above sea level. The telescope's geographic location is 34° 13' 20" N latitude and 118° 3' 24" W longitude.
Many individuals and companies have donated time, equipment and services to bring the TIE telescope system to full operation. The equipment is continually being upgraded and improved to ensure the highest quality of images. It is the intent of the TIE Project to allow students to perform scientifically valid measurements with the equipment.
History of the TIE Telescope
The 24 inch Cassegrain telescope was designed in 1963 by Jim Westphal and Bruce Rule of Caltech for the Apollo space program. Completed in Caltech workshops in 1964, it was installed on White Mountain in the Sierra Nevada Range where is was used by Westphal and Bruce Murray of JPL in infrared studies of the Moon's surface. Having successfully determined that the surface of the Moon would support the landing of the Apollo Lunar Module and subsequent astronaut moonwalks, the telescope was moved to the Mount Wilson Observatory where it was used for two decades by Caltech graduates.
Other major projects carried out with the telescope include the first infrared study of a comet and the first mapping of the center of our Milky Way galaxy. The 24 inch telescope has also been used to determine the rotational periods of a number of asteroids.
In 1988 the telescope was dismantled and stored in the large dome at Palomar Mountain. In 1993 Dr. Robert Jastrow, Director of the Mount Wilson Observatory, acquired the telescope from Caltech for the TIE Project.
With the reinstallation of the telescope on Mount Wilson, Gil Clark's dream of the Telescopes in Education Project became a reality. The 24 inch telescope was refurbished and fitted with a Newtonian focus cage, and an advanced computer controlled drive mechanism installed. The telescope and its new auxiliary equipment, including the CCD camera system, were placed into service and students immediately started using the system.
Today, the 24" telescope is completely computer controlled and can be operated remotely through the use of computer and modem. Remote Astronomy Software available from Software Bisque, Golden, Colorado, is used to bring control of the TIE telescope into the classroom. One component of this software, "TheSky," also allows teachers and students to prepare an observing schedule based on the date and time of the scheduled observation.
Doing Science with the TIE Telescope
The key to the usefulness of the TIE Project for remote astronomy is the ability to download images taken by a charge-coupled device (CCD) electronic camera that is attached to the 24" telescope. This scientific-grade electronic camera is also remotely operated by the user through the same computer and modem used to control the telescope. An additional software component, "SkyPro," runs simultaneously with TheSky and gives the users full control of the CCD camera.
The CCD camera is a Santa Barbara Instruments Group (SBIG) ST-6, which contains a 375 x 242 pixel array with a field of view of 13.9 x 10.5 arc minutes.
A second camera, an SBIG ST-8, will soon be available primarily for use in planetary studies. It will be mounted to a 6" refractor to be attached to the 24" telescope tube structure. The ST-8 contains a 1530 x 1020 pixel array. This camera may also be available for use on the 24" telescope for high resolution scientific studies.
Details on CCD Astronomy can be found later in this User's Guide and Workbook.
Using the SystemEquipment and Software Required
Groups and individuals who wish to use the TIE system need to have the following equipment and software available for remote operation:
- IBM PC-type computer, 386 or better, running Windows or Windows '95.
- SVGA monitor and driver card: these will provide the best viewing of the high quality images that will be downloaded during the observing session.
- At least 4 megabytes of RAM, 8 megabytes for Pentiums operating Windows '95: this is necessary for operation of the software that controls the telescope.
- 9600-baud or faster modem
- Modem and Phone Telephone Lines: a voice line, in addition to the modem line, is required to facilitate communication with the volunteer telescope operator during sessions.
- Remote Astronomy Software package, including TheSky and SkyPro, available from Software Bisque, Golden, Colorado; contact Software Bisque at 800 843-7599.
The Remote Astronomy Software package is available at a special discount rate to educators and students participating in the TIE Project; to obtain the discount, please inform the sales representative that the software is being purchased for educational use in conjunction with the TIE Project.
Familiarize Yourself with TheSky and SkyPro
Once the proper hardware and software has been acquired and the remote astronomy software is loaded on the system, it is important to get familiar with the software. The user should work with both TheSky and SkyPro software prior to the on-line test.
Schedule an On-Line Test
The On-Line test can be scheduled by calling the Mount Wilson Institute as described above. The session will typically be scheduled early in an evening when an operator is present at the TIE Project facility on Mount Wilson.
The on-line test is important because the user and the operator can determine if the remote setup is functioning properly, and will help correct any problems if it is not. It is best if two phone lines can be used, one for the modem and one for simultaneous voice communication with the telescope operator. That way, problems can be quickly solved without having to disconnect the modem and so forth.
Schedule the Observing Session
After a successful on-line test, the user can contact the Mount Wilson Institute as described above and schedule an observing session. When requesting a reservation, it is necessary to provide two or three possible observing dates and times. Reservations are accepted up to four months in advance. It is wise to reserve observing time early to assure that preferred dates are available.
Prior to the Observing Session
Time on the TIE telescope is valuable. It is highly recommended that an observing schedule be prepared before the observing session takes place. TheSky software package makes it easy to determine which objects will be visible in the night sky during a particular date and time of the observing session. Without an observing schedule, or verification that an object is indeed available for viewing, observing time can easily be wasted.
Project 1, "Basic Use of the TIE 24" Telescope System" provides further information that will help the observing session run smoothly.
While preparing an observing schedule, please note the location of the object in the sky. The TIE telescope must slew from object to object. If one object, for example, is low in the east and the next object is low in the west, it may take a minute or so for the telescope to slew to that next object. It is best if the selected objects are near each other. It is also wise to image objects which soon set early in the session. Thus, image objects in the west first, then work toward the east to ensure objects are not setting before the image can be made
Select Objects Above 30° N
Due to limitations of the equipment and some obscuration of the sky near the horizon, only objects that have an altitude of 30° N or more may be selected for viewing. The object's altitude may be determined easily by clicking on the object in TheSky which brings up the "Object Identification" box. Within this box is various information about the object, including the "Az, Alt" of the object. The "Az, Alt" shows the Azimuth (compass heading) and the Altitude (height in degrees, minutes and seconds above the horizon) for that particular object. The second set of numbers, the Altitude, will confirm if the object is available for imaging if they read greater than 30° N.
Hint: Under the Input menu, set the Date and Time (Mt. Wilson is Pacific Time Zone) of your scheduled on-line session to see a representation of the sky over Mt. Wilson as it will appear during your observations with the TIE telescope. Uncheck the box that indicates TheSky will use the System Time. Check the Location, making sure it reads Current Location: Mount Wilson.
Warning: When finished with planning the observing session, be sure to reset TheSky's Date and Time so that the System Time is used prior to dialling into the dome.
Remotely Link to the Telescope
Users should follow the directions included in Software Bisque's Remote Astronomy Software package for details on remote linking with the telescope and CCD camera. Follow the instructions included with the Remote Astronomy Software package regarding communications port selection, baud rate selection, and entry of the TIE Telescope Modem phone number.
In order for TheSky and SkyPro to remotely communicate with the TIE Telescope, the "Local Serial Port Controller" (LSPC) software must first establish modem connection with the TIE Telescope Modem. The LSPC enables TheSky and SkyPro to simultaneously operate and control both the telescope and the CCD camera.
Open TheSky and Link with the Telescope
Once the LSPC has established modem connection to the TIE telescope modem, a welcome screen will be displayed. Click "OK." Another window will appear, indicating the TheSky may now be used to control the telescope. Click "OK." Minimize the LSPC so that TheSky icon is visible. Start TheSky by double-clicking the mouse on TheSky icon.
Follow the instructions included with the Remote Astronomy Software package regarding location selection and communication language (ACL or Astronomy Control Language) for TheSky.
Establish a link with the TIE telescope by choosing "Link" in the "Telescope" menu bar, then "Establish." If TheSky properly communicates with the TIE telescope, cross hairs should appear on the remote computer screen, and the Night Vision Mode invoked (everything on the screen is turned to a shade of red). Night Vision mode can be cancelled by choosing "Options," "Night Vision."
If a link cannot be established, check the connection to the TIE Telescope modem. Be sure to check under "Telescope" menu, "Data" that the Communication Box shows "ACL" or "Astronomy Command Language Telescope." The telescope operator at Mount Wilson is trained to assist in troubleshooting problems, and may make suggestions for the user to follow to solve the problem.
Open SkyPro and Link with the Camera
Use "Alt-Tab" as a shortcut to returning to the Program Manager (Windows), or minimize TheSky window (Windows '95), so that the SkyPro icon is visible. Start SkyPro by double-clicking the mouse on the SkyPro icon.
A pair of icons will appear on the lower left of the open window of the display. Use these icons to navigate between the two programs, TheSky and SkyPro, by clicking on the desired icon with the mouse. In Windows '95 and for some versions of Remote Astronomy Software these icons may not appear. As an alternative, click on the middle button (between the minimize and close buttons) at the top right corner of the window. A "Task Bar" will appear at the bottom of the screen. Do this for both TheSky and SkyPro windows. The task bar for each program can then be clicked on to select either TheSky or SkyPro.
Establish a link with the TIE CCD camera by choosing "Link" in the "Camera" menu bar, then "Establish." Once SkyPro properly communicates with the TIE CCD camera, a dialog box indicating "Adjust Head Offset" will appear momentarily and then disappear. Next, choose "Temperature" in the "Camera" menu bar, then set the temperature to a value indicated by the telescope operator, typically between -20 and -30°C.
Set the Camera Temperature
A status bar at the bottom of the window, on the right side, shows the temperature set point and the power. Check to be sure the power reading is below 80%. If it is higher, raise the temperature setting (less negative) until the power reading is below 80%. This will ensure proper control of the thermoelectric cooler. The objective is to maintain the lowest operating temperature of the CCD without exceeding 80% power usage for extended periods of time.
Initialze the Color Filter Wheel
The filter wheel will automatically initialize itself just after the Head Offset Adjustment is performed. If the filter wheel is to be used in the session, select Filter menu, Setup and be sure that SBIG CFW-6A (Motorized) is selected. Close and select the Filter menu, then confirm that the order of filters is Red, Green, Blue, Clear and None. Next, check that the filter wheel is in the Clear position by selecting Clear and click on "OK." The operator will then inform the user that the filter has moved into position. Use this procedure to select other filters during the session as required to complete projects or studies.
If a link cannot be established to the CCD camera, check the connection to the TIE Telescope modem. Check that in the "Camera" menu, "Setup" that the camera selected is "SBIG ST-6 CCD Camera." In the same window, check that the port selection matches the port you have assigned to the modem. Again, the telescope operator will help troubleshoot problems if necessary.
Bring TheSky to operation in the front window by using the icons or the task barjust mentioned.
Start Controlling the Telescope
TheSky can now be used to slew the TIE telescope to any object desired by clicking on the object, displaying the Object Identification box, and choosing the "Slew To" button. The "Find" command, located amongst the tiles on the left side of the display, can be used to manually enter an object name or designation, and then choosing the "Find" button at the bottom of the dialog box will open the Object Identification box for that particular object. Then, as before, use the "Slew To" button to command the TIE telescope to move to the new object.
Take an Exposure
After the telescope has completed slewing, the CCD camera must be commanded to take a picture of the object for transmission of the image to the remote computer. Follow the instructions included with the Remote Astronomy Software package regarding Camera Setup.
Once the link is established and the temperature set, the camera can be commanded to take an image. Select "Take Exposure" in the "Camera" menu bar, then input the desired exposure time, in seconds. Also check that:
"Frame Mode" is set to "Automatic,"
"Resolution" is set to "High," and
"Background & Range is set to "Automatic."
The telescope operator will suggest exposure times based experience and on the object brightness.
After the "OK" button is pressed, imaging is automatic. First, a dark frame is taken (as a calibration procedure) and digitized, then the light frame is taken (the actual image) and digitized. See the following section on Introduction to CCD Astronomy for details concerning the theory and operation of the CCD camera. After the light frame is taken, downloading of the image begins. This may take 2 to 5 minutes to complete, depending on the user's modem speed and quality of the phone connection.
Do not be tempted to switch back to TheSky to select and slew to another object to save time, as this often causes a system crash and then the downloading of the image will be terminated. It is best to wait until the image is completely downloaded and saved to the user computer's hard disk before moving back to TheSky for selection and slewing to the next object.
Save the Object to Disk
Once downloading is complete, the image will be displayed on the user's computer monitor. If the image is satisfactory, save the image file to disk by selecting "File" menu, "Save As" and assign an appropriate name. The saved file may be recalled for later viewing, printing and manipulation. The image file downloaded to the remote computer is the only file created and is not duplicated at the TIE telescope side. In fact, the TIE telescope operator cannot see the image just downloaded. Please indicate any issues with focus, centering or other problems so the operator can diagnose and correct such problems if necessary.
During the observing session, the telescope operator may determine that re-focusing of the system is necessary. This may be due to changing temperature or user feedback that the image does not look in focus. Follow the instructions below for ending the session, and once the operator has completed the focus check, follow the instructions above for establishing the link to the telescope and CCD camera again.
Ending the Remote Observing Session
After the last image is completely downloaded and saved, terminate the camera link by selecting "Link" and "Terminate" under the "Camera" menu bar. Then Exit SkyPro. From TheSky terminate the telescope link by selecting "Link" and "Terminate" from the "Telescope" menu bar, and Exit TheSky.
Maximize the LSPC window, and hang up with the TIE Telescope Modem by selecting "Hang Up" from the "Modem" menu bar. Exit the LSPC by choosing the "Exit" command from the "File" menu bar.
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