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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

23711 results found.

  1. EP240506a: EP-WXT detection of a new fast X-ray transient
  2. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  3. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  4. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  5. Fermi trigger No 736564880: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  7. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  8. Fermi trigger No 736461232: Global MASTER-Net observations report
  9. Fermi GRB 240504A: Global MASTER-Net observations report
  10. Fermi trigger No 736472503: Global MASTER-Net observations report
  11. GRB 240503A: AstroSat CZTI detection
  12. Fermi trigger No 736387941: Global MASTER-Net observations report
  13. GRB 240502A: GOTO optical upper limit
  14. Fermi trigger No 736379109: Global MASTER-Net observations report
  15. GRB 240502C: GOTO possible optical counterpart candidates
  16. Fermi GRB 240502B: Global MASTER-Net observations report
  17. Fermi GRB 240502A: Global MASTER-Net observations report
  18. GRB 240501B: GRBAlpha detection
  19. GRB 240430A: GRBAlpha detection
  20. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet Transient Candidates
  21. Integral GRB240502.23: Global MASTER-Net observations report
  22. Fermi GRB 240501A: Global MASTER-Net observations report
  23. Fermi trigger No 736197684: Global MASTER-Net observations report
  24. GRB 240426A: VZLUSAT-2 detection
  25. GRB 240425A: VZLUSAT-2 detection
  26. GRB 240501B: AstroSat CZTI detection
  27. GRB 240408B: VZLUSAT-2 detection
  28. GRB 240407A: VZLUSAT-2 detection
  29. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  30. GRB 240425A: GRBAlpha detection
  31. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  32. Fermi GRB 240428A: Global MASTER-Net observations report
  33. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  34. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  35. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  36. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  37. EP240426b: EP-WXT detection of a new fast X-ray transient
  38. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  39. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  40. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  41. GRB 240426A: AstroSat CZTI detection
  42. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  43. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  44. GRB 240414A: NOEMA detection
  45. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  46. EP240426a: GMG optical upper limit
  47. LVK S240422ed: Further Swift-XRT followup of three sources
  48. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  49. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  51. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  52. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  53. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  54. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  55. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  56. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  57. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  58. Fermi trigger No 735697285: Global MASTER-Net observations report
  59. GRB 240419B: Swift-BAT refined analysis
  60. GRB 240421B: Swift-BAT refined analysis
  61. GRB 240422A: Glowbug gamma-ray detection
  62. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  63. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  64. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  65. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  66. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  67. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  68. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  69. LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated.
  70. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  71. GRB 240421B: GRBAlpha detection
  72. IceCube Alert 240424.08: Global MASTER-Net observations report
  73. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  74. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  75. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  76. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  77. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  78. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  79. GRB 240419A: Swift-BAT refined analysis
  80. GRB 240418A: Swift-BAT refined analysis
  81. LXT240402A/GRB240402B: Chandra X-ray detection
  82. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  83. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  84. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  85. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  86. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  87. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  88. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  89. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  90. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  91. Fermi trigger No 735470374: Global MASTER-Net observations report
  92. GRB 240421A: Glowbug gamma-ray detection
  93. GRB 240414A: radio detection with the VLA
  94. GRB 240414A: LBT optical detection
  95. GRB 240419B : MITSuME Akeno optical upper limits
  96. GRB 240415B: Swift-XRT observations
  97. Fermi GRB 240422A: Global MASTER-Net observations report
  98. Fermi GRB 240421B: Global MASTER-Net observations report
  99. Swift GRB 240421B: Global MASTER-Net observations report
  100. GRB 240421B: Fermi GBM Observation

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