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NRAO Newsletter

Volume Vol#, Issue Iss# Day# Month# Year#

Upcoming Events

New Era of AGN Science with Vera C. Rubin LSST
July 24 - 26, 2023 | Charlottesville, VA

The Evolution of Gas in and around Galaxies
July 31 - Aug 4, 2023 | Stanley, ID

GBO Single Dish Summer School
August 6 - 11, 2023 | Green Bank, WV and Online

15th DiFX Users and Developers Meeting
September 11 - 15, 2023 | Socorro, NM

First Mexican ngVLA Meeting
September 25 - 27, 2023 | Morelia, Mexico

NRAO Community Days at IRyA-UNAM
September 28 - 29, 2023 | Morelia, Mexico

ALMA at 10 years: Past, Present, and Future
December 4 - 8, 2023 | Puerto Varas, Chile

NRAO at the June 2023 Albuquerque AAS

From the Archives

Brian Kent, Mark Lacy, and Phil McCarten

NRAO astronomers, staff, students, and users gather in Albuquerque, New Mexico to collaborate and present their latest research.

The 242nd American Astronomical Society meeting was held in Albuquerque, New Mexico in June 2023. NRAO users, staff, students, and astronomers participated in sessions on radio astronomy in New Mexico, the VLA Sky Survey featuring COSMIC and VLITE (session website and video), an ngVLA community forum (slides and feedback), and the NRAO Town Hall. NRAO Jansky Fellows Julia Blue Bird (CHILES), Pallavi Patil (AGN), and Dillon Dong (Transients with VLASS) all gave outstanding talks at the conference. AAS participants also traveled for a highly anticipated event - a tour of the world-renowned VLA Observatory.

Albuquerque AAS 242 Conference Photos

Brian Kent

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ngVLA Project News

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Collaborations in Mexico

To promote and drive the participation of Mexico in the ngVLA, the Institute of Radioastronomy and Astrophysics (IRyA-UNAM) invites the Mexican community to a kick-start conference "First Mexican meeting en route to the Next Generation Very Large Array", to be held in Morelia, Mexico, September 25-27. Invited and contributed presentations will focus on design and performance aspects of the telescope, and the science it could enable. Conference details are now available.

After the conference, IRyA-UNAM will host NRAO Community Days on September 28-29. This event is especially designed for astronomers who do not regularly utilize radio data in their research. The workshop will provide an overview of NRAO instruments (VLA, ALMA) including new capabilities, plus a discussion of data reduction and pipelines, including aspects of polarimetry and self-calibration. The second day will also include hands-on tutorials for ALMA and VLA data reduction and imaging. Workshop details are available on the NRAO Science website.

VLA/VLBA to ngVLA transition discussion at AAS 242 Albuquerque

Slides from the VLA/VLBA to ngVLA transition plan presentation at the AAS 242 conference in Albuquerque, New Mexico are now available. We encourage community members to provide feedback on the broad features of the transition plan.

ngVLA-SKA New Eyes on the Universe - slides available

Slides and video from the Vancouver New Eyes on the Universe conference are now available on the meeting website.

ngVLA Science - Time Domain and Structural Studies of Compact Symmetric Objects

(a) The CSO Family. Solid features indicate firm distinctions. Dotted features indicate hypotheses. (b) VLBA image of an example CSO 2.0.

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Compact symmetric objects (CSOs) are jetted-AGN with overall sizes of less than 1 kpc, showing clear evidence of emission on both sides of the central engine, and in which the observed radiation is not strongly beamed toward the observer. CSOs have been studied for decades but their importance to AGN studies has been largely overlooked.

Two problems hindered progress: (i) Distinguishing the role of CSOs in the menagerie of compact radio sources (CSSs, GPSs, MSOs, etc.). (ii) The CSO class was introduced (Wilkinson et al. 1994, Readhead et al. 1996) to include only objects whose observed emission is not strongly boosted towards the observer, but the class has been significantly contaminated by blazars. To overcome these problems, we (Kiehlmann et al. 2023a) studied 3000+ claimed CSOs and likely CSO candidates, applying strict morphological, variability, and speed criteria, and yielding 79 bona fide CSOs.

Analyzing these 79, we (Kiehlmann et al. 2023b, Readhead et al. 2023; see figure) confirmed an earlier finding that CSOs bifurcated into an edge-dimmed low luminosity class (CSO 1) and an edge-brightened high luminosity class (CSO 2). We also found that CSO 2s can be split into class CSO 2.0, with prominent hot-spots at the leading edges of narrow jets and/or narrow lobes; and class CSO 2.2, without prominent hot-spots but with broad jets and/or lobes. An intermediate class, CSO 2.1, exhibits mixed properties. Also, 17 bona fide CSOs are in complete radio samples suitable for rigorous tests. These tests reveal a sharp cutoff in CSO sizes at ~500 pc, plus numbers and redshift distributions showing that >99% of CSO 2s are distinct from other classes of jetted-AGN.

Thus the formation of most CSO 2s is different in some critical way from most jetted-AGN. A possibility is a limited fuel supply, such as that of individual stars in tidal disruption events. CSO properties are consistent with this scenario (Readhead et al. 2023). Other possible energy sources include tapping the spin of massive black holes, and a constrained energy supply in the accretion disk in a manner similar, but not identical, to dwarf novae.

The time is now ripe for a revolution in AGN studies through exploitation of time domain plus structural studies of CSOs. On the immediate horizon, extending these studies an order of magnitude deeper in CSO luminosity is possible with the VLBA. To more fully test our hypothetical evolutionary model will require extending a further two orders of magnitude deeper in CSO luminosity. Large surveys, made possible by the DSA2000, followed up with deep VLBI imaging up to 100 GHz, made possible only with the ngVLA, will be essential.

Since 2015 the acronym ngVLA has appeared in 950+ publications indexed in the SAO/NASA Astrophysics Data System. This article continues a regular feature intended to showcase some of those publications. We are especially interested in showcasing work done by early-career researchers. The collection of showcase articles can be viewed online. Anyone wishing to volunteer to author a feature should contact Joan Wrobel.

ALMA Program News

ALMA      Photo Credit: S. Otarola Photography

ALMA Status

ALMA is observing in June in its current C-7 configuration and plans to expand to C-8 (baselines 110-8500) by month's end. The Cycle 10 Call for Proposals closed on 10 May for observations from October 2023 to September 2024.

ALMA Cycle 10 Call for Proposals status

Proposals are being reviewed by designated reviewers. Results of the proposal review are expected to be delivered to proposers in August 2023.

Conference ALMA at 10 years: Past, Present, and Future Dec 4-8, 2023

The conference ALMA at 10 years: Past, Present, and Future will be held in Puerto Varas, Chile, on 4-8 December 2023. The conference covers ALMA's first decade of science operations while looking forward to the evolution of ALMA's capabilities in its second decade. Abstract submission for contributed talks closed on May 31, 2023. 279 abstracts for contributed talks were received! The Scientific Organizing Committee (SOC) will review the abstracts, and the selected speakers (approximately 45-50 slots are available) will be notified in July 2023.

Registration for in-person attendance has reached capacity and is closed. Registration for on-line participation, including posters, is open until November 2, 2023. Please visit the registration web page to submit a poster abstract for on-line participation.

Semester 2023B Proposal Review


The NRAO has completed the Semester 2023B proposal review and time allocation process for the Very Large Array (VLA) and the Very Long Baseline Array (VLBA).

For the VLA the D-configuration will be available in the 23B semester and 101 new proposals were received by the 1 February 2023 submission deadline, including one large and fifteen time critical (triggered) proposals. The oversubscription rate (by proposal number) was 2.4 and the proposal pressure (hours requested over hours available) was 1.9, both of which are similar to recent semesters.

For the VLBA 39 new proposals were submitted. The oversubscription rate was 2.0 and the proposal pressure was 1.8, similar to past semesters.

There was some demand for the time made available on space observatories through inter-observatory agreements, and seven proposals requesting time on ALMA, HST, or Swift (together with AUI/NRAO telescope time) were submitted.

Proposals submitted to the GBO were assessed through the same process. Fifty-nine proposals for the GBT were received for the 23B Semester. The oversubscription rate is 3.1 and the proposal pressure is 2.4. For information on proposals for GBT observations see the GBO website.

The proposals were reviewed for scientific merit by ten Science Review Panels (SRPs) and for technical feasibility by NRAO staff. These reviews were completed in February - March 2023 and then considered by the Time Allocation Committee (TAC) during a face-to-face meeting on 17-18 April 2023. The TAC - comprising the 10 SRP chairs - was charged with recommending a science program for Semester 2023B to the Observatory Director. The recommended program was reviewed and approved on 10 May 2023.

A disposition letter was sent to the Principal Investigator and Co-Investigators of each proposal on 17 May 2023 and a TAC report containing information for proposers and observers, including statistics and telescope pressure plots, was released the same day. The approved science program for the VLA and the VLBA has been posted to the NRAO science website. The authors, title, abstract, and scheduled hours for each approved proposal can be accessed from the Proposal Finder Tool.

The Student Observing Support program continues to be available for NRAO observing programs and we encourage Principal Investigators of highly ranked VLA and VLBA proposals to consider applying for support.

The NRAO welcomes community feedback on the proposal review and time allocation process. Please provide such feedback via the Proposal Review department of the NRAO Helpdesk.

Joint Proposals with NICER


The Neutron Star Interior Composition Explorer (NICER) is an X-ray experiment on the International Space Station (ISS) dedicated to high-resolution timing and spectroscopy of neutron stars and other rapidly variable X-ray sources in the 0.2–12 keV band. Cycle 6 of the NICER General Observer (GO) program solicits proposals for observations with NICER addressing all areas of astrophysics, with at least 7.5 Ms of available time and a limited amount of funding available.

Starting in 24A, joint proposals may be submitted requesting time on NICER. A maximum time of 250 ksec can be allocated per year.

Automated self-calibration available for ALMA and VLA

Figure 1. ALMA Band 6 (1.3 mm) images of the NGC 2071 IR star forming region from ALMA project 2018.1.01038.S (Cheng et al. 2022). The top image is without self-calibration, while the lower image is from the automated self-calibration within the pipeline.

Figure 2. VLA K-band images (1.3 cm) of the galaxy NGC 1068 from project 18B-163 (Chiaraluce et al. 2020). The top image is without self-calibration, while the lower image is from the automated self-calibration within the pipeline.

The Science Ready Data Products (SRDP) project and the NRAO pipeline team are excited to announce the addition of automated self-calibration to the ALMA and VLA imaging pipelines. We are providing users with a preview of this capability prior to the normal fall pipeline release. The automated self-calibration capability is immediately available through the ALMA User-Defined Imaging capability from the NRAO archive. Thus, self-calibration of the science targets will be attempted for any qualifying dataset that is imaged with this service. Phase-only self-calibration is performed using the continuum data, and solutions are applied to the spectral line data as well. Users will be provided the continuum and spectral line images with and without self-calibration applied to enable them to evaluate the impact of self-calibration.

The initial automated self-calibration capability is available for single pointing observations only and is expected to perform well for modest to high signal-to-noise data. Future extensions to self-calibration will include mosaics and better performance for long baseline configurations. We note that self-calibration has the greatest impact on the continuum data and the effect for spectral line data is generally quite modest (unless the spectral lines themselves are extremely bright). Further documentation of the capability is provided on the NRAO science pages.

We are also providing the CASA 6.5.3 package with the pipeline included so that users are able to explore this capability on their own. While the imaging service through the NRAO archive only supports ALMA at present, the pipeline task itself supports self-calibration of VLA data. Therefore, users can use this package to run the VLA imaging pipeline with self-calibration if desired. We emphasize, however, that this package is only validated to support the ALMA User-Defined Imaging capability and VLA imaging. Any other data processing, i.e., standard calibration of ALMA and VLA data, should be performed using the observatory recommended CASA versions. If users have any questions regarding the pipeline or imaging service, they are encouraged to contact the NRAO helpdesk (Topic: VLA, Department: VLA pipeline for VLA queries and Topic: Data Products, Department: ALMA Data Products for ALMA queries).

The development and implementation of self-calibration for the pipeline was a joint effort between the NRAO SRDP Project, the ALMA Pipeline Working Group, and the ALMA and NRAO pipeline development teams.

CASA Newsletter Issue 12

From the Archives

Issue 12 of the CASA Newsletter is now available, with articles on new release notes, performance tests, tools, and more. Please contact the team with any feedback or comments.

Free guided tours at the Very Large Array

From the Archives

Summer Ash; NRAO/AUI/NSF

Free guided tours for the public have returned at the VLA on the 1st and 3rd Saturday of each month at 10 a.m., 12 p.m., and 2 p.m. Advance admission required (purchase here) but no tour reservation necessary. Just head to the Visitor Center auditorium to join you preferred time. These tours last approximately one hour and give visitors unique insight into the past, present, and future of the VLA.

2023 NRAO/GBO Postdoctoral Symposium


Kim Emig, Bang Nhan, Emily Moravec

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Postdocs enjoy a dish climb on a VLA antenna, guided by NRAO astronomer Dr. Rick Perley.

The 18th Postdoctoral Science Symposium was held on May 15 - 17, 2023 at the National Radio Astronomy Observatory in Socorro, New Mexico in a hybrid format. The annual symposium brings together the resident and non-resident Jansky fellows and NRAO and Green Bank Observatory (GBO) postdocs in order to highlight their cutting edge research, share ideas, and establish collaborations. Participants toured the Very Large Array and Very Long Baseline Array in Pie Town during their visit.

From the Archives

From the Archives

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About this month's photo: A happy group of Charlottesville students in the 1972 summer student program: Bottom row l-r: Changlin Wey, Patrick Yeung, Tom Gandet, Tom Bania, David Gibson. Middle row l-r: Steven Peterson, John Chandler, Vicky Diadiuk, Linda Lucignani, Michael True. Top row l-r: Pamela Bonnell, Alma Zook, Rosemary Kennett, Stanley Hansen, Lars Petterson, Philip Stickney, Daniel Grayson.

For over six decades, NRAO has welcomed summer students to our sites to work on a wide variety of research projects with NRAO staff mentors. Our 46 incoming 2023 students will participate in a rich and unique research and professional development experience. The program kicked off with the "Radio Astronomy Bootcamp," a week-long workshop in Green Bank with lectures and hands-on observing. Students then work on their research in Green Bank, Charlottesville, and Socorro under the supervision of their mentors. Since its inception in 1959, the summer student program has engaged over 1,300 young people in scientific research, and many NRAO summer students have gone on to distinguished careers in astronomy and other physical sciences.

From the Archives is an ongoing series illustrating NRAO and U.S. radio astronomy history via images selected from our collections of individuals' and institutional papers. If readers have images they believe would be of interest to the Archives, please contact Ellen Bouton.

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