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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

2748 results found.

  1. GRB 240514E: A possible candidate BD-21 1074
  2. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  3. GRB 240514B: GOTO candidate optical counterpart
  4. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  5. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  6. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  7. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  8. GRB 240502C: GOTO possible optical counterpart candidates
  9. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  10. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  11. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  12. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  13. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  14. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  15. EP240426a: YAHPT optical upper limit
  16. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  17. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  18. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  19. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  20. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  21. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  22. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  23. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  24. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  25. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  26. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  27. LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
  28. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  29. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  30. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  31. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  32. GRB 240419A: Possible ATCA radio detection
  33. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  34. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  35. GRB240418A - Candidate afterglow from NIRES
  36. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  37. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  38. EP240417a: YAHPT Optical Upper Limits
  39. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  40. EP240416a: Kinder optical counterpart candidate
  41. GRB 240415A: Mondy optical transient detection
  42. LXT 240402A/GRB 240402B: Swift follow-up observations
  43. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  44. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  45. GRB 240414A: Swift detection of a burst
  46. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  47. EP240408a: Swift follow-up observation
  48. X-ray transient EP240331a: Kinder optical upper limits
  49. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  50. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  51. X-ray transient EP240315a: e-MERLIN radio observations
  52. Transient EPW20240219aa: REM optical/NIR further observations
  53. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  54. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  55. Swift satellite in safe mode
  56. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  57. X-ray transient EP240315a: orphan FXT?
  58. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  59. AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
  60. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  61. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  62. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  63. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  64. Transient EPW20240219aa: Liverpool Telescope non-detection and limiting magnitude
  65. Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
  66. GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
  67. GRB 240214A/1H 0451-560: MAXI/GSC detection
  68. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  69. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  70. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  71. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  72. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  73. GRB 240101B: Swift-BAT refined analysis
  74. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  75. IceCube-231202A - IceCube observation of a high-energy neutrino candidate track-like event
  76. IceCube-231125A - IceCube observation of a high-energy neutrino candidate track-like event
  77. GRB 231117A: Keck spectroscopy of afterglow candidate
  78. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  79. GRB231115A: Liverpool Telescope imaging
  80. GRB 231115A: AGILE/MCAL upper limits
  81. GRB 231115A: significance of INTEGRAL localization alignment with M82
  82. GRB 231111A: TNG tentative redshift
  83. GRB231110A: WFST Observation and upper limits
  84. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  85. IceCube-231027A - IceCube observation of a high-energy neutrino candidate track-like event
  86. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  87. GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
  88. GRB 230911C: ATCA detection of possible radio counterpart
  89. IC231004A: Classification of AT2023uqf/ZTF23abidzvf as a rapidly-evolving supernova with CSM interaction
  90. IceCube-231014A - IceCube observation of a high-energy neutrino candidate track-like event
  91. IceCube-231004A - IceCube observation of a high-energy neutrino candidate track-like event
  92. transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
  93. LIGO/Virgo/KAGRA S230904n: Classification of the candidate AT2023rkw with DBSP
  94. Correction to Fermi GBM Statement for Trigger 716527670/230916144
  95. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  96. IceCube-230914A - IceCube observation of a high-energy neutrino candidate track-like event
  97. GRB 230911D: NuSTAR Detection of Prompt Emission
  98. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  99. GRB 230812B: Assy optical observations, possible SN rise
  100. GRB 230812B: SAO RAS observations, possible re-brightening

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