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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"

12097 results found.

  1. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  2. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  3. GRB 240425A: Fermi GBM Final Real-time Localization
  4. Fermi trigger No 735697285: Global MASTER-Net observations report
  5. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  6. LIGO/Virgo/KAGRA S240413p: DESGW DECam Follow-Up
  7. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  8. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  9. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  10. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  11. IceCube Alert 240424.08: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  13. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  14. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  15. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  16. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  17. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  18. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  19. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  20. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  21. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  22. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  23. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  24. Fermi-LAT gamma-ray observations of IceCube-240419A
  25. GRB 240414A: AMI-LA radio observations
  26. GRB 240414A: LBT optical detection
  27. GRB 240415A: Swift-XRT refined Analysis
  28. GRB 240421B: AstroSat CZTI detection
  29. GRB240421B: BOOTES-5/JGT optical upper limit
  30. Fermi GRB 240421A: Global MASTER-Net observations report
  31. EP240417a: no counterpart detection by SOAR
  32. EP240420a: Xinglong decaying optical counterpart
  33. GRB 240421B: Swift detection of a burst
  34. EP240420a: Nanshan optical counterpart observations
  35. EP240420a: GWAC-F50A optical upper limit
  36. Fermi trigger No 735280430: Global MASTER-Net observations report
  37. IceCube Alert 240419.98: Global MASTER-Net observations report
  38. GRB 240419B: Swift-XRT refined Analysis
  39. GRB 240419A: Swift-XRT refined Analysis
  40. GRB 240418A: Swift-XRT refined Analysis
  41. GRB 240419B: Swift detection of a burst
  42. EP240417a: YAHPT Optical Upper Limits
  43. GRB240418A: YAHPT Upper Limits
  44. GRB 240419A: VLT optical afterglow detection
  45. GRB 240419A: Swift detection of a burst
  46. Swift GRB240418.85: Global MASTER-Net observations report
  47. GRB 240418A: Swift detection of a burst
  48. Fermi GRB 240417A: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  50. GRB 240414A: Glowbug gamma-ray detection
  51. EP240416a: EP-WXT detection of a fast X-ray transient
  52. GRB 240414A: AbAO optical upprer limit
  53. GRB 240415A: OHP/T193 optical observations
  54. GRB 240415A: SAO RAS optical observations
  55. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  56. GRB 240414A: Fermi GBM Observation
  57. Fermi GRB 240415A: Global MASTER-Net observations report
  58. GRB 240414B: Fermi GBM Final Real-time Localization
  59. GRB 240415A: Prompt Swift-XRT observations
  60. GRB 240414A: Swift-XRT refined Analysis
  61. GRB240414A : J-band upper limits from WINTER
  62. IPN triangulation of GRB 240410A
  63. Fermi-LAT gamma-ray observations of IceCube-240412A
  64. EP240413a: EP-WXT detection of a fast X-ray transient
  65. GRB 240414A: Swift detection of a burst
  66. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  67. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  68. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  69. EP240408a: GROND detection of a candidate counterpart
  70. EP240408a: Swift follow-up observation
  71. EP240408a: EP-WXT detection of a fast X-ray transient
  72. GRB 240408B: AstroSat CZTI detection
  73. Fermi GRB 240407A: Global MASTER-Net observations report
  74. Fermi-LAT gamma-ray observations of IceCube-240327B
  75. Fermi-LAT gamma-ray observations of IceCube-240327A
  76. GRB 240331A: GRBAlpha detection
  77. Konus-Wind detection of LXT 240402A/GRB 240402B
  78. LXT 240402A: MASTER optical observations with AGN in error-box
  79. Fermi GRB 240402A: Global MASTER-Net observations report
  80. X-ray transient EP240331a: Kinder optical upper limits
  81. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  82. EP240331A: MASTER optical observations
  83. X-ray transient EP20240331a: MeerLICHT optical upper limits
  84. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  85. GRB 240324A: AstroSat CZTI detection of a short burst
  86. GRB 240331A: AstroSat CZTI detection
  87. GRB 240329A: AstroSat CZTI detection
  88. X-ray transient EP240315a: continued ATCA monitoring
  89. X-ray transient EP240315a: e-MERLIN radio observations
  90. GRB 240320A: Glowbug gamma-ray detection
  91. Fermi GRB 240320A: Global MASTER-Net observations report
  92. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  93. Fermi trigger No 732657380: Global MASTER-Net observations report
  94. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  95. X-ray transient EP240315a: ATCA detection of radio counterpart
  96. GRB 240320A: Fermi GBM Final Real-time Localization
  97. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  98. X-ray transient EP 240315a: Chandra observations
  99. GRB 240317C: Glowbug gamma-ray detection
  100. X-ray transient EP240315a: PRIME near infrared detection

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