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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"

27776 results found.

  1. GRB 240519A: AstroSat CZTI detection
  2. EP240518a: possibly identified with a flare star by EP-FXT
  3. EP240518a: EP-WXT detection of a new X-ray transient
  4. GRB 240516A: Swift-BAT refined analysis
  5. GRB 240516A ATCA radio observations
  6. IPN triangulation of GRB 240514B (short)
  7. GRB 240513A: Swift ToO observations
  8. GRB 240517A: Fermi GBM Final Real-time Localization
  9. Konus-Wind detection of GRB 240513A
  10. GRB 240516A: AstroSat CZTI detection
  11. GRB 240516A: Swift-XRT refined Analysis
  12. GRB 240514E: A possible candidate BD-21 1074
  13. GRB 240516A: Fermi GBM Observation
  14. GRB 240511A: Observations from GTC/OSIRIS+
  15. GRB 240516A: GOTO optical upper limit
  16. LIGO/Virgo/KAGRA S240422ed: GRID non-detection and upper limits
  17. GRB 240516A: Swift detection of a burst
  18. Swift GRB240516.15: Global MASTER-Net observations report
  19. GRB 240511A: radio detection of afterglow candidate
  20. GRB 240514E: MAXI/GSC detection of a probable afterglow
  21. GRB 240514B: GRBAlpha detection
  22. GRB 240514B: Fermi GBM Detection
  23. GRB 240513A: Swift-XRT observations
  24. GRB 240514D: AstroSat CZTI detection
  25. GRB 240514C: Fermi GBM Final Real-time Localization
  26. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  27. GRB 240514B: Fermi GBM Final Real-time Localization
  28. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  29. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  30. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  31. GRB 240514A: Fermi GBM Final Real-time Localization
  32. GRB 240513A: Tiled Swift observations
  33. GRB 240513A: Fermi-LAT detection
  34. GRB 240511A: Fermi GBM Observation
  35. GRB 240511A: Swift-BAT refined analysis
  36. GRB 240513B: Fermi GBM Final Real-time Localization
  37. GRB 240513A: AstroSat CZTI detection
  38. GRB 240511A: J-band observations with WINTER
  39. GRB 240511A: Enhanced Swift-XRT position
  40. GRB 240511A : MITSuME Akeno optical upper limits
  41. GRB 240511A: Swift-XRT refined Analysis
  42. GRB 240511A: optical afterglow detection from the NOT
  43. Swift GRB 240511A: Global MASTER-Net observations report
  44. GRB 240511A: Prompt enhanced Swift-XRT position
  45. GRB 240511A: Swift detection of a burst
  46. GRB 240511A: Fermi GBM Final Real-time Localization
  47. EP240506a: Xinglong optical upper limit
  48. GRB 240504A: Fermi GBM Observation
  49. EP240506a: Archival radio searching
  50. EP240506a: BOOTES Network optical upper limit
  51. IPN triangulation of GRB 240504A
  52. EP240506a: EP-WXT detection of a new fast X-ray transient
  53. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  54. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  55. GRB 240503A: AstroSat CZTI detection
  56. GRB 240504A: Fermi GBM Final Real-time Localization
  57. GRB 240415A 1.3m DFOT Optical upper limit
  58. GRB 240502C: Fermi GBM Final Localization
  59. GRB 240501B: GRBAlpha detection
  60. GRB 240430A: GRBAlpha detection
  61. GRB 240502B: Fermi GBM Final Real-time Localization
  62. GRB 240502A: Fermi GBM Final Real-time Localization
  63. GRB 240426A: VZLUSAT-2 detection
  64. GRB 240425A: VZLUSAT-2 detection
  65. GRB240430A: Fermi GBM Final Localization
  66. GRB 240501B: AstroSat CZTI detection
  67. GRB 240501A: Fermi GBM Final Real-time Localization
  68. GRB 240408B: VZLUSAT-2 detection
  69. GRB 240407A: VZLUSAT-2 detection
  70. X-ray transient EP240414a: Detection of associated supernova
  71. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  72. GRB 240425A: GRBAlpha detection
  73. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  74. GRB 240429A: Fermi GBM Final Real-time Localization
  75. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  76. LIGO/Virgo/KAGRA S240429an: Retraction of GW compact binary merger candidate
  77. GRB 240428A: Fermi GBM Final Real-time Localization
  78. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  79. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  80. EP240426b: AST3-2 optical upper limit
  81. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  82. EP240426b: EP-WXT detection of a new fast X-ray transient
  83. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  84. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  85. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  86. GRB 240426A: AstroSat CZTI detection
  87. EP240426a: YAHPT optical upper limit
  88. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  89. GRB 240414A: NOEMA detection
  90. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  91. EP240426a: GMG optical upper limit
  92. LVK S240422ed: Further Swift-XRT followup of three sources
  93. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  94. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  95. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  96. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  97. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  98. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  99. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  100. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam

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