Congratulations “Govies” on your selection to the West Virginia Governor’s STEM Institute (WVGSI)! The Green Bank Observatory sessions of the WVGSI will be held June 8-19 for rising tenth graders, and July 18-30 for rising ninth graders. Even though we will be virtual this year, we promise a challenging and fun experience in which YOU will be engaged in conducting astronomical research using a 20 Meter diameter radio telescope! You will have the opportunity to make new friends from around the state, network with undergraduate students, teachers, and scientists.
Your next step is to complete and return a permission form. You and your parents will need to complete and sign and return to GBO. You can email the form or mail it to: Green Bank Observatory, PO Box 2, Green Bank, WV 24944, attn: Sue Ann Heatherly
The sky is the limit! Join Undergraduate STEM students in a variety of activities and discussions. You pick from several choices each day. What interests you?
You can even lead a seminar for others!
Dig a little deeper into STEM fields with 3-day activity series exploring Astro techniques, Electronics and Biology! We rotate all Govies through 3 Directed Studies.
You will work in a small team to conduct research using a robotic 20 Meter Telescope, and optical telescopes on the Skynet Robotic Telescope Network.
Teachers, undergrads, and GBO scientists will advise you but the project is yours!
On most days, our GSI will follow the same schedule. Here’s a snapshot from our planning spreadsheet. Please note that even “on screen time” will not be on-screen entirely, as we will be doing activities, or collecting data.
MUSTANG-2 is a 223-feedhorn bolometer (continuum) camera with a bandpass from 75 to 105 GHz. The full bandpass is available here.
MUSTANG-2 is inherently a mapping instrument and observes by scanning “on-the-fly” (OTF). Our most common scan pattern is that of a Lissajous Daisy that can observe objects from our resolution (9″) to several arcminutes in size. For scans of ~a degree, we have switched to a raster scan. If you would like to consider another mapping strategy, please contact a member of the MUSTANG-2 instrument team to inquire about it. The instantaneous field of view (FOV) is just over 4 arcminutes (4.2′).
All MUSTANG-2 proposals are shared-risk and must be approved by the MUSTANG-2 instrument team. Furthermore, the MUSTANG-2 instrument team must be included as co-investigators on the proposal. Conversely, the MUSTANG-2 team will reduce the data and provide appropriate data products (principally a calibrated map, transfer function, and beam characterization) to the proposal team. End-to-end data reduction is currently fairly involved. We will work to provide documentation on data processing and hope to eventually allow proposers to process their own data.
MUSTANG-2 instrument team
The instrument team currently consists of:
Please contact Charles Romero at cromero -at- nrao -dot- edu or Brian Mason at bmason -at- nrao -dot- edu for inquiries.
Overhead, observing constraints
The overhead for MUSTANG-2 is dominated by initial setup and calibration. We generally recommend a minimum session length of 2 hours. Proposals should quote an observing efficiency of 50% (or 100% overheads relative to on-target time).
The MUSTANG-2 team will principally focus on the technical feasibility of a proposal and make suggestions accordingly. The technical justification on a proposal should reference publicly available mapping speeds, e.g. from MUSTANG_2 mapping speeds memo. The GBT sensitivity calculator does not currently incorporate MUSTANG-2 mapping speeds.
Note: If you are interested in using MUSTANG-2 in the future please see the note below about the status and plans for future GBT observing.
Table Of Contents
MUSTANG-2 at a glance
MUSTANG-2 is a 223-feedhorn bolometer camera which was commissioned on the GBT in spring 2016, and has been offered for observations on a shared risk basis, in collaboration with the instrument team, since the 2018A GBO proposal call. Several features distinguish it from its predecessor, MUSTANG:
A new, microstrip-coupled detector design yields higher sensitivity and less susceptibility to environmental microphonics.
Detectors are feedhorn coupled, with the sum of two linear polarizations measured by a single TES per feed.
The instantaneous field of view is 4 arcminutes (vs 42 arcseconds for MUSTANG)
The receiver design incorporates a tilted refrigerator and receiver rotator, resulting in much lower dependence of cooling performance on telescope elevation.
The detector readout is the first astronomical use of microwave resonators to multiplex TES bolometers.
MUSTANG-2 has been developed by a collaboration including the University of Pennsylvania, NIST, NRAO, the University of Michigan, and Cardiff University. All critical MUSTANG-2 systems have already been proven in operation on the GBT in early 2015 during an engineering run using a partially populated version of the receiver (“MUSTANG-1.5”, which had 64 populated feed horns).
MUSTANG-2 mapping speeds
Some basic performance information is as follows:
MUSTANG-2’s primary scanning method is that of a Lissajous Daisy of varying radii. The mapping speed profiles have been scaled to a zenith opacity of 0.1 and elevation of 45 degrees.
This sensitivity assumes an effective smoothing of 10″.0 FWHM. If heavier smoothing is acceptable the sensitivity is better by a factor of (FWHM/10.0 arcsec).
Historically, we have reported mapping speeds based on the RMS within a circle of radius 2 arcminutes. These values have now been extended to a range of scan sizes.
Scan size (radius, arcminutes)
Mapping speed in central 2 arcminutes (μK hr1/2)
Mapping speeds are calculated based on the RMS in the central 2 arcminutes. For small scans, this region has roughly uniform noise.
Extended signal on scales up to 5′ should be imaged with reasonable fidelity, but faint signal more extended than this may be difficult to detect. Bright emission (20 mJy/beam or more) can be reconstructed over scales of many arcminutes. The angular resolution of MUSTANG on the GBT is typcally 9″ (FWHM) and the instantaneous field of view is a 4′ diameter circle.
Recovery of signal depends on data processing.
Allowing for weather and calibration and observing overheads, observers should conservatively allow an observing efficiency of 50% (i.e., assume equal times integrating on source, and for calibrating and general overheads – so 100% overheads relative to observing time). A minimum setup and calibration time of 1 hour is generally required for each observing session.
Daytime observing at 90 GHz is currently not advised. The changing solar illumination gives rise to thermal distortions in the telescope structure which make calibrating 90 GHz data extremely difficult. Useful 3mm observations are currently only possible between 3h after sunset and a half hour past sunrise.
Please contact Charles Romero (cromero – nrao – edo) or Brian Mason (bmason – nrao – edu) with further questions.
The Status of Future GBT Open-Skies Observing
In order to cope with an evolving funding landscape the GBT is in the process of moving to a model which relies upon a larger fraction of private and collaborative (“pay-to-play”) partnerships. It is expected that a significant fraction of GBT time, depending on the future level of NSF funding, will remain open under something like the current proposable, open-skies arrangement; however the mix of observing capabilities that is available under this arrangement is TBD. If you are interested in forming or contributing to such a partnership to ensure continued access to MUSTANG-2 on the GBT, please contact the director of the Green Bank Observatory, Karen O’Neil.
Venus is an enigma. It’s the planet next door and yet reveals little about itself. An opaque blanket of clouds smothers a harsh landscape pelted by acid rain and baked at temperatures that can liquify lead.
Now, new observations from the safety of Earth are lifting the veil on some of Venus’ most basic properties. By repeatedly bouncing radar off the planet’s surface over the last 15 years, a UCLA-led team has pinned down the precise length of a day on Venus, the tilt of its axis and the size of its core. The findings are published today in the journal Nature Astronomy.
Astronomical surveys mapping regions of the Galaxy have been collected and studied for decades. These surveys allow researchers to compare previous data, further characterize objects or images of the sky, and learn more through statistical analysis. For the National Science Foundation’s Green Bank Telescope (GBT) Diffuse Ionized Gas Survey (GDIGS), researchers took advantage of the power of the GBT, located in Pocahontas County, West Virginia, to better understand the impact of massive stars in the Milky Way.