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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"

2623 results found.

  1. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  2. LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
  3. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  4. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  5. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  6. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  7. GRB 240419A: Possible ATCA radio detection
  8. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  9. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  10. GRB240418A - Candidate afterglow from NIRES
  11. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  12. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  13. EP240417a: YAHPT Optical Upper Limits
  14. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  15. EP240416a: Kinder optical counterpart candidate
  16. GRB 240415A: Mondy optical transient detection
  17. LXT 240402A/GRB 240402B: Swift follow-up observations
  18. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  19. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  20. GRB 240414A: Swift detection of a burst
  21. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  22. EP240408a: Swift follow-up observation
  23. X-ray transient EP240331a: Kinder optical upper limits
  24. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  25. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  26. X-ray transient EP240315a: e-MERLIN radio observations
  27. Transient EPW20240219aa: REM optical/NIR further observations
  28. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  29. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  30. Swift satellite in safe mode
  31. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  32. X-ray transient EP240315a: orphan FXT?
  33. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  34. AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
  35. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  36. IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
  37. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  38. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  39. Transient EPW20240219aa: Liverpool Telescope non-detection and limiting magnitude
  40. Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
  41. GRB 240209A: Classification of AT2024cew/GOTO24pw as Type Ia-pec supernova
  42. GRB 240214A/1H 0451-560: MAXI/GSC detection
  43. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  44. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  46. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  47. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  48. GRB 240101B: Swift-BAT refined analysis
  49. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  50. IceCube-231202A - IceCube observation of a high-energy neutrino candidate track-like event
  51. IceCube-231125A - IceCube observation of a high-energy neutrino candidate track-like event
  52. GRB 231117A: Keck spectroscopy of afterglow candidate
  53. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  54. GRB231115A: Liverpool Telescope imaging
  55. GRB 231115A: AGILE/MCAL upper limits
  56. GRB 231115A: significance of INTEGRAL localization alignment with M82
  57. GRB 231111A: TNG tentative redshift
  58. GRB231110A: WFST Observation and upper limits
  59. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  60. IceCube-231027A - IceCube observation of a high-energy neutrino candidate track-like event
  61. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  62. GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
  63. GRB 230911C: ATCA detection of possible radio counterpart
  64. IC231004A: Classification of AT2023uqf/ZTF23abidzvf as a rapidly-evolving supernova with CSM interaction
  65. IceCube-231014A - IceCube observation of a high-energy neutrino candidate track-like event
  66. IceCube-231004A - IceCube observation of a high-energy neutrino candidate track-like event
  67. transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
  68. LIGO/Virgo/KAGRA S230904n: Classification of the candidate AT2023rkw with DBSP
  69. Correction to Fermi GBM Statement for Trigger 716527670/230916144
  70. LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
  71. IceCube-230914A - IceCube observation of a high-energy neutrino candidate track-like event
  72. GRB 230911D: NuSTAR Detection of Prompt Emission
  73. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 230812B: Assy optical observations, possible SN rise
  75. GRB 230812B: SAO RAS observations, possible re-brightening
  76. GRB 230812B: SAO RAS optical observations
  77. GRB230816A: Possible host and GIT detection of optical counterpart
  78. GOTO confirmation and possible host galaxy of GRB230812B optical afterglow
  79. GRB 230805B: SAO RAS optical observations
  80. GRB 230728A: NOT optical observations and possible host galaxy
  81. IceCube-230727A - IceCube observation of a high-energy neutrino candidate track-like event
  82. IceCube-230724A - IceCube observation of a high-energy neutrino candidate track-like event
  83. IceCube-230725A - IceCube observation of a high-energy neutrino candidate track-like event
  84. GRB 230723B: Optical afterglow candidate from CAHA
  85. GRB 230723B: Optical limit from CAHA
  86. Swift Trigger 1178410: possible GRB 230709A
  87. IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
  88. IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event
  89. IceCube-230707A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 230628E - VLT spectroscopic observations
  91. LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
  92. Fermi GBM-230619: A soft subthreshold candidate potentially associated with a subthreshold LIGO/Virgo compact binary merger candidate
  93. ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Swift/UVOT detection
  94. AT2023lcr: Pan-STARRS & ATLAS Observations
  95. ZTF23aaoohpy/AT2023lcr: Keck/LRIS spectroscopy and redshift
  96. LIGO/Virgo/KAGRA S230615az: GOTO candidate counterparts
  97. IceCube-230603A - IceCube observation of a high-energy neutrino candidate track-like event
  98. IceCube-230524A - IceCube observation of a high-energy neutrino candidate track-like event
  99. LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
  100. GRB 230512A: Kitab possible afterglow candidate

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