Changes between Version 63 and Version 64 of RoboDIMM
- Timestamp:
- Jan 19, 2011, 11:16:08 AM (16 years ago)
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RoboDIMM
v63 v64 457 457 Dual RoboDIMMs 458 458 459 On August 25, 2010, t he two RoboDIMMs were set up south of PS1 spointing at Polaris along the west side of the dome. To get the star to appear just off the widest part of the dome the DIMMs were placed about 20' off the road in the area leading toward the former location of the ATST tower. To locate the DIMM measuring seeing near-dome the DIMM was moved east until the images were blocked by the dome then moved west until they were just clear. The other DIMM was placed 5' to the west.460 461 During the time the data was collected the dome was basically stationary while the observer , Natalia, was taking pinhole data on the moon. Because the moon was rising the near-dome measurements were made off the surface of the rear shutter.459 On August 25, 2010, two RoboDIMMs were set up south of PS1 and pointed at Polaris along the west side of the PS1 dome. The goal was to have one DIMM measure seeing through the boundary layer above the dome surface while the other DIMM measured along a path outside the boundary layer. To locate the DIMM measuring seeing near-dome the DIMM was moved east until the images were blocked by the dome then moved west until they were just clear. The other DIMM was placed 5' to the west. 460 461 During the time the data was collected the dome was basically stationary while the observer was taking pinhole data on the moon. Because the moon was rising the near-dome measurements were made off the surface of the rear shutter. Seeing was poor during while the data was collected. Also, because the RoboDIMMs were at ground level there was a significant ground seeing effect. The data seem to indicate that any degradation of seeing due to the skin seeing effect is insignificant compared with other factors. 462 462 463 463 * [https://svn.pan-starrs.ifa.hawaii.edu/trac/ipp/attachment/wiki/RoboDIMM/Triple-DIMM-skin-wws-8.25.10.jpg DIMM data with wind speed] … … 468 468 469 469 470 To measure the variation in seeing across Reber Circle a static RoboDIMM (Location 0 on map) was positioned just off the asphalt NE of Airglow. Simultaneous measurements were made with the static DIMM and a second RoboDIMM at a series of four locations approximately 8 feet apart in a N-NW line (Locations 1-4on map).470 To measure the variation in seeing across Reber Circle a static RoboDIMM (Location A on map) was positioned just off the asphalt NE of Airglow. Simultaneous measurements were made with the static DIMM and a second RoboDIMM at a series of four locations approximately 8 feet apart in a N-NW line (Locations B-E on map). 471 471 472 472 === __September 2, 2010__ === 473 473 474 Measurements were made at Locations 1 and 2. Winds all night were light, <3.5 m/s. Throughout the night both RoboDIMMs and the DNSM were looking at stars high in the sky. The DNSM was pointed at Altair all night. Both RoboDIMMs measured Antares during the data taking at Location 1. Around 6:30 UT some high clouds moved in. I believe this accounts for the degradation in seeing and the lack of DNSM data points. Because the DIMMs, particularly the static one, were struggling to keep their stars on the focal plane both were moved to Altair which was further south.474 Measurements were made at Locations A, B, and C. Winds all night were light, <3.5 m/s. Throughout the night both RoboDIMMs and the DNSM were looking at stars high in the sky. The DNSM was pointed at Altair all night. Both RoboDIMMs measured Antares during the data taking at Location B. Around 6:30 UT some high clouds moved in. I believe this accounts for the degradation in seeing and the lack of DNSM data points. Because the DIMMs, particularly the static one, were struggling to keep their stars on the focal plane both were moved to Altair which was further south. 475 475 476 476 * [https://svn.pan-starrs.ifa.hawaii.edu/trac/ipp/attachment/wiki/RoboDIMM/Reber-seeing-9.2.10.jpg Seeing Plot] … … 479 479 480 480 Locations 2,3, and 4. 481 During the RoboDIMM observations I made last night at Reber Circle the wind was 3-6 m/s as measured at the DNSM and out of the SE. After struggling for nearly an hour trying to get the RoboDIMMs to track Vega, a star nearly as close to zenith as Altair, the star the DNSMwas tracking, I gave up and moved to Arcturus which was dropping to 482 the west. The disparity in reported seeing values in the attached plot during this period appear to reflect the difference between the RoboDIMMs and the DNSM in the altitude of their respective target stars. Despite looking through quite a bit of atmosphere the RoboDIMMs seem to be fairly consistent. 483 484 At 7:45 both RoboDIMMs were moved to Vega. The DNSM target star continued to be Altair. The lack of DNSM data points from 6:45-8:45 appear to be due to high clouds. The PS1 observer, Angie, reported high cirrus during the evening. Even without a large number of DNSM data points the r0 values appear to coincide well with those reported by both RoboDIMMs. The two DIMMs were 32 ft apart during the final data set yet seem to agree fairly well. The offsets in values, particularly around 8:45, appear to be due to clock issues. Although the GPS time program is set to synch every minute, around this time I noticed a couple instances where the clocks were nearly 2 minutes apart. For most of the time, it should be noted, the differences are less than 20 sec. 481 During the RoboDIMM observations at locations A, C, D, and E the wind was out of the SE at 3-6 m/s as measured at the DNSM. After struggling for nearly an hour trying to get the RoboDIMMs to track Vega, a star nearly as close to zenith as Altair, the star the DNSM was tracking, the DIMMs were moved to Arcturus which was dropping to the west. The disparity in reported seeing values in the attached plot during this period appear to reflect the difference between the RoboDIMMs and the DNSM in the altitude of their respective target stars. Despite looking through quite a bit of atmosphere the RoboDIMMs seem to be fairly consistent with each other. 482 483 At 7:45 both RoboDIMMs were moved to Vega. The DNSM target star continued to be Altair. The lack of DNSM data points from 6:45-8:45 appear to be due to high clouds. The PS1 observer reported high cirrus during the evening. Even without a large number of DNSM data points the r0 values appear to coincide well with those reported by both RoboDIMMs. The two DIMMs were 32 ft apart during the final data set yet seem to agree fairly well. The offsets in values, particularly around 8:45, appear to be due to clock issues. Although the GPS time program is set to synch every minute, around this time a couple instances were noted where the clocks were nearly 2 minutes apart. For most of the time, however, the differences are less than 20 sec. 485 484 486 485 * [https://svn.pan-starrs.ifa.hawaii.edu/trac/ipp/attachment/wiki/RoboDIMM/Reber-seeing-9.7.10.jpg Seeing Plot] … … 488 487 === __September 10, 2010__ === 489 488 490 Location 4 (labelled Location 2 on jpg) 491 492 The attached plots shows data collected from the RoboDIMMs separated by a distance of about 40' on Reber Circle. Winds were close to 6 m/s early in the evening but dropped to just over 2 m/s by the end. High clouds necessitated moving the DIMMs to a number of different targets as well as repeatedly restarting the program and re-acquiring stars. The last hour was spent tracking a star quite low in the sky 489 Data was collected from the RoboDIMMs separated by a distance of approximately 32' on Reber Circle (locations A and E). Winds were close to 6 m/s early in the evening but dropped to just over 2 m/s by the end. High clouds necessitated moving the DIMMs to a number of different targets as well as repeatedly restarting the program and re-acquiring stars. The last hour was spent tracking a star quite low in the sky 493 490 494 491 * [https://svn.pan-starrs.ifa.hawaii.edu/trac/ipp/attachment/wiki/RoboDIMM/Reber-seeing-9.10.10.jpg Seeing Plot] … … 496 493 === __September 14, 2010__ === 497 494 498 40 ft NW (labelled Location 2 on jpg) 499 500 Attached are last nights results. The winds were ~10m/s out of the E-SE during the evening. The static DIMM was sheltered from the wind somewhat by the PS2 containers. I believe this accounts for the differences between the DIMMs between 6:30 and 7. At that time I moved from a Arcturus which was fairly low to Rasalhague which was closer to zenith. Both DIMMs were affected by the wind but the one toward the center was buffeted more. Despite this, it appears that the measurements coincide well and it seems that we can conclude that seeing is relatively consistent across Reber Circle. 495 Data was collected again at locations A and E, approximately 32' apart on Reber Circle. The winds were ~10m/s out of the E-SE during the evening. The static DIMM (location A) was sheltered from the wind somewhat by the PS2 containers. This seems to account for the differences between the DIMMs between 6:30 and 7UT. At that time the DIMMs were moved from a Arcturus which was fairly low to Rasalhague which was closer to zenith. Both DIMMs were affected by the wind but the one nearer the center of the Circle (location E) was buffeted more. Despite this, it appears that the measurements coincide well and it seems that we can conclude that seeing is relatively consistent across Reber Circle. 501 496 502 497 * [https://svn.pan-starrs.ifa.hawaii.edu/trac/ipp/attachment/wiki/RoboDIMM/Reber-seeing-9.14.10.jpg Seeing Plot] … … 512 507 === __October 14, 2010__ === 513 508 514 Airglow roof and Reber Circle center 515 516 In the attached plot the DNSM data is corrected to zenith and converted to FWHM, the RoboDIMM data is converted to FWHM, and the PS1 FWHM is corrected for airmass. Throughout the night the winds were < 5 m/s out of the NE. The large gap in the DNSM data is due to high clouds obscuring Altair. At 8 UT the DNSM moved to Diphda and resumed data collection. The high clouds moved across the RoboDIMM's path to Vega a few times requiring that the DIMMs be restarted. During the time period that RoboDIMM data was collected PS1 was pointed to the SE. 509 Data was collected from the roof of the Airglow building (location F) and the approximate center of Reber Circle (location G). In the plot the DNSM data is corrected to zenith and converted to FWHM, the RoboDIMM data is converted to FWHM, and the PS1 FWHM is corrected for airmass. Throughout the night the winds were < 5 m/s out of the NE. The large gap in the DNSM data is due to high clouds obscuring Altair. At 8 UT the DNSM moved to Diphda and resumed data collection. The high clouds moved across the RoboDIMM's path to Vega a few times requiring that the DIMMs be restarted. During the time period that RoboDIMM data was collected PS1 was pointed to the SE. 517 510 518 511 * [https://svn.pan-starrs.ifa.hawaii.edu/trac/ipp/attachment/wiki/RoboDIMM/corrected-Reber-seeing-10.14.10.jpg Seeing Plot]
