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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').
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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"

11756 results found.

  1. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  2. GRB 240529A: AstroSat CZTI detection
  3. GRB 240527B: Swift-XRT afterglow detection
  4. GRB 240529A: Swift detection of a burst with an optical counterpart
  5. Swift GRB240529.12: Global MASTER-Net observations report
  6. GRB 240527B: Fermi GBM Observation
  7. GRB 240527B: Fermi-LAT detection
  8. Fermi trigger No 738348224: Global MASTER-Net observations report
  9. Fermi trigger No 738330463: Global MASTER-Net observations report
  10. GRB 240523A: Swift-XRT refined Analysis
  11. Fermi trigger No 737996942: Global MASTER-Net observations report
  12. GRB 240521A: GECAM-B detection of a long burst
  13. GRB 240516B: AstroSat CZTI detection
  14. LIGO/Virgo/KAGRA S240515m: Upper limits from Swift/BAT-GUANO
  15. LIGO/Virgo/KAGRA S240514x: Upper limits from Swift/BAT-GUANO
  16. LIGO/Virgo/KAGRA S240513ei: Upper limits from Swift/BAT-GUANO
  17. LIGO/Virgo/KAGRA S240520cv: Identification of a GW compact binary merger candidate
  18. GRB 240519A: AstroSat CZTI detection
  19. Fermi GRB 240517A: Global MASTER-Net observations report
  20. Konus-Wind detection of GRB 240513A
  21. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  22. Fermi trigger No 737523389: Global MASTER-Net observations report
  23. GRB 240516A: Swift detection of a burst
  24. Swift GRB240516.15: Global MASTER-Net observations report
  25. MAXI GRB240514.78: Global MASTER-Net observations report
  26. GRB 240514E: MAXI/GSC detection of a probable afterglow
  27. GRB 240514D: AstroSat CZTI detection
  28. GRB 240514C: Fermi GBM Final Real-time Localization
  29. Fermi GRB 240514B: Global MASTER-Net observations report
  30. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  31. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  32. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  33. LAT GRB240513.31: Global MASTER-Net observations report
  34. GRB 240513A: Fermi-LAT detection
  35. GRB 240511A: Fermi GBM Observation
  36. GRB 240511A: Swift-BAT refined analysis
  37. Fermi trigger No 737277727: Global MASTER-Net observations report
  38. GRB 240513A: AstroSat CZTI detection
  39. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  40. Fermi trigger No 737196587: Global MASTER-Net observations report
  41. Fermi trigger No 737168073: Global MASTER-Net observations report
  42. GRB 240511A: Swift-XRT refined Analysis
  43. Fermi trigger No 737152719: Global MASTER-Net observations report
  44. GRB 240511A: Swift detection of a burst
  45. GRB 240511A: Fermi GBM Final Real-time Localization
  46. Fermi trigger No 737111207: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  48. EP240506a: CrAO ZTSH optical upper limit
  49. EP240506a: EP-WXT detection of a new fast X-ray transient
  50. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  51. Fermi trigger No 736564880: Global MASTER-Net observations report
  52. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  53. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  54. Fermi GRB 240504A: Global MASTER-Net observations report
  55. Fermi trigger No 736472503: Global MASTER-Net observations report
  56. GRB 240503A: AstroSat CZTI detection
  57. LXT 240402A / GRB 240402B: VLT X-shooter redshift of host
  58. GRB 240502C: GOTO possible optical counterpart candidates
  59. GRB 240502A long GRB detected by INTEGRAL
  60. Fermi GRB 240501A: Global MASTER-Net observations report
  61. Fermi trigger No 736197684: Global MASTER-Net observations report
  62. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  63. GRB 240501B: AstroSat CZTI detection
  64. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  65. Fermi-LAT gamma-ray observations of IceCube-240424A
  66. LIGO/Virgo/KAGRA S240422ed: A transient discovered from Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  67. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  68. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  69. EP240426b: EP-WXT detection of a new fast X-ray transient
  70. GRB 240426A: AstroSat CZTI detection
  71. XMM-Newton observation of EP240426a
  72. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  73. EP240426a: GMG optical upper limit
  74. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  75. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  76. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  77. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  78. GRB 240425A: Fermi GBM Final Real-time Localization
  79. Fermi trigger No 735697285: Global MASTER-Net observations report
  80. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  81. LIGO/Virgo/KAGRA S240413p: DESGW DECam Follow-Up
  82. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  83. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  84. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  85. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  86. IceCube Alert 240424.08: Global MASTER-Net observations report
  87. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  88. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  89. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  90. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  91. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  92. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  93. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  94. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  95. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  96. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  97. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  98. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  99. Fermi-LAT gamma-ray observations of IceCube-240419A
  100. GRB 240414A: AMI-LA radio observations

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