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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"

12091 results found.

  1. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  2. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  3. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  4. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  5. IceCube Alert 240424.08: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  7. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  8. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  9. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  10. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  11. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  12. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  13. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  14. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  15. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  16. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  17. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  18. Fermi-LAT gamma-ray observations of IceCube-240419A
  19. GRB 240414A: AMI-LA radio observations
  20. GRB 240414A: LBT optical detection
  21. GRB 240415A: Swift-XRT refined Analysis
  22. GRB 240421B: AstroSat CZTI detection
  23. GRB240421B: BOOTES-5/JGT optical upper limit
  24. Fermi GRB 240421A: Global MASTER-Net observations report
  25. EP240417a: no counterpart detection by SOAR
  26. EP240420a: Xinglong decaying optical counterpart
  27. GRB 240421B: Swift detection of a burst
  28. EP240420a: Nanshan optical counterpart observations
  29. EP240420a: GWAC-F50A optical upper limit
  30. Fermi trigger No 735280430: Global MASTER-Net observations report
  31. IceCube Alert 240419.98: Global MASTER-Net observations report
  32. GRB 240419B: Swift-XRT refined Analysis
  33. GRB 240419A: Swift-XRT refined Analysis
  34. GRB 240418A: Swift-XRT refined Analysis
  35. GRB 240419B: Swift detection of a burst
  36. EP240417a: YAHPT Optical Upper Limits
  37. GRB240418A: YAHPT Upper Limits
  38. GRB 240419A: VLT optical afterglow detection
  39. GRB 240419A: Swift detection of a burst
  40. Swift GRB240418.85: Global MASTER-Net observations report
  41. GRB 240418A: Swift detection of a burst
  42. Fermi GRB 240417A: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  44. GRB 240414A: Glowbug gamma-ray detection
  45. EP240416a: EP-WXT detection of a fast X-ray transient
  46. GRB 240414A: AbAO optical upprer limit
  47. GRB 240415A: OHP/T193 optical observations
  48. GRB 240415A: SAO RAS optical observations
  49. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  50. GRB 240414A: Fermi GBM Observation
  51. Fermi GRB 240415A: Global MASTER-Net observations report
  52. GRB 240414B: Fermi GBM Final Real-time Localization
  53. GRB 240415A: Prompt Swift-XRT observations
  54. GRB 240414A: Swift-XRT refined Analysis
  55. GRB240414A : J-band upper limits from WINTER
  56. IPN triangulation of GRB 240410A
  57. Fermi-LAT gamma-ray observations of IceCube-240412A
  58. EP240413a: EP-WXT detection of a fast X-ray transient
  59. GRB 240414A: Swift detection of a burst
  60. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  61. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  62. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  63. EP240408a: GROND detection of a candidate counterpart
  64. EP240408a: Swift follow-up observation
  65. EP240408a: EP-WXT detection of a fast X-ray transient
  66. GRB 240408B: AstroSat CZTI detection
  67. Fermi GRB 240407A: Global MASTER-Net observations report
  68. Fermi-LAT gamma-ray observations of IceCube-240327B
  69. Fermi-LAT gamma-ray observations of IceCube-240327A
  70. GRB 240331A: GRBAlpha detection
  71. Konus-Wind detection of LXT 240402A/GRB 240402B
  72. LXT 240402A: MASTER optical observations with AGN in error-box
  73. Fermi GRB 240402A: Global MASTER-Net observations report
  74. X-ray transient EP240331a: Kinder optical upper limits
  75. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  76. EP240331A: MASTER optical observations
  77. X-ray transient EP20240331a: MeerLICHT optical upper limits
  78. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 240324A: AstroSat CZTI detection of a short burst
  80. GRB 240331A: AstroSat CZTI detection
  81. GRB 240329A: AstroSat CZTI detection
  82. X-ray transient EP240315a: continued ATCA monitoring
  83. X-ray transient EP240315a: e-MERLIN radio observations
  84. GRB 240320A: Glowbug gamma-ray detection
  85. Fermi GRB 240320A: Global MASTER-Net observations report
  86. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  87. Fermi trigger No 732657380: Global MASTER-Net observations report
  88. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  89. X-ray transient EP240315a: ATCA detection of radio counterpart
  90. GRB 240320A: Fermi GBM Final Real-time Localization
  91. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  92. X-ray transient EP 240315a: Chandra observations
  93. GRB 240317C: Glowbug gamma-ray detection
  94. X-ray transient EP240315a: PRIME near infrared detection
  95. Fermi GRB 240318A: Global MASTER-Net observations report
  96. GRB 240317A: AstroSat CZTI detection
  97. GRB 240315B: AstroSat CZTI detection
  98. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  99. Fermi GRB 240317B: Global MASTER-Net observations report
  100. Fermi trigger No 732299243: Global MASTER-Net observations report

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