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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"

34125 results found.

  1. GRB 220403B: Mondy optical upper limit
  2. GRB 220403B: 1.5m OSN optical observation
  3. GRB 220404A: Swift-BAT refined analysis
  4. GRB 220403B: Kitab optical observations
  5. GRB 220405A: Fermi GBM Final Localization
  6. GRB 220403B: Swift-BAT refined analysis
  7. GRB 220404B: Fermi GBM Final Real-time Localization
  8. GRB 220403B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  9. GRB 220403B: Fermi GBM detection
  10. GRB 220404A: Swift detection of a burst
  11. GRB 220403B: Swift-XRT refined Analysis
  12. GRB 220403B: LBT observations
  13. Swift GRB 220403B: Global MASTER-Net observations report
  14. GRB 220403C (or A): Swift/BAT-GUANO detection outside the coded FOV
  15. GRB 220403B: Nanshan/NEXT optical afterglow power-law decay
  16. GRB 220403A: Tautenburg observations
  17. GRB 220403B: optical detection by D50
  18. GRB 220403B: Swift detection of a burst with an optical counterpart
  19. Fermi GRB 220403A: Global MASTER-Net observations report
  20. GRB 220403A: Fermi GBM Final Real-time Localization
  21. GRB 220401A: Swift/BAT-GUANO detection outside the coded FOV
  22. GRB 220401A: Fermi GBM observation
  23. Swift Trigger 1100848 is likely not a GRB
  24. Fermi GRB 220401B: Global MASTER-Net observations report
  25. GRB 220401B: Fermi GBM Final Real-time Localization
  26. GRB 220401A: Fermi GBM Final Localization
  27. Fermi Gamma-ray Burst Monitor trigger 220331776/670444627 is not a GRB
  28. GRB 220331A: Fermi GBM Final Real-time Localization
  29. Fermi GRB 220330A: Global MASTER-Net observations report
  30. GRB 220330A: Fermi GBM Final Real-time Localization
  31. GRB 220325A: GRANDMA observations
  32. GRB 220320A: Detection by VZLUSAT-2
  33. Konus-Wind observation of GRB 220320A
  34. GRB 220325A: Swift/UVOT Upper Limits
  35. GRB 211024B: Host galaxy redshift from X-shooter/VLT
  36. GRB 220325A: Swift-BAT refined analysis
  37. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, TSHAO, AbAO)
  38. GRB 220325A: Tautenburg observations
  39. GRB 220326A: Fermi GBM Final Localization
  40. GRB 220325A: LCO Optical Upper Limits
  41. GRB 220325A: Swift-XRT refined Analysis
  42. GRB 220325A: 1.3m DFOT Optical upper limit
  43. GRB 220325B: Fermi GBM Final Localization
  44. Fermi GBM Sub-Threshold Detection of GRB 220325A
  45. GRB 220325A: Enhanced Swift-XRT position
  46. GRB 220325A: MASTER Global Robotic Net optical observations
  47. GRB 220324A: AstroSat CZTI detection
  48. GRB 220325A: Swift detection of a burst
  49. GRB 220323A: AstroSat CZTI detection
  50. GRB 220319A: GRANDMA observations
  51. GRB 220323A: AGILE/MCAL detection
  52. IPN triangulation of GRB 220320A
  53. GRB 220323A: Fermi GBM Final Real-time Localization
  54. GRB 220319A: Swift-BAT refined analysis
  55. GRB 220316A: AstroSat CZTI detection
  56. GRB 220320A: AstroSat CZTI detection
  57. GRB 220317A: Fermi GBM detection
  58. GRB 220321A: Fermi GBM Final Localization
  59. GRB 220319A: MITSuME Akeno optical upper limits
  60. GRB 220319A: LCO Optical Upper Limit
  61. GRB 220319A: Mondy optical uper limit
  62. GRB 220319A: Swift-XRT refined Analysis
  63. GRB 220319A: Enhanced Swift-XRT position
  64. GRB 220319A: MASTER Global Robotic Net optical observations
  65. GRB 220319A: Swift detection of a burst
  66. GRB 220317A: Swift/BAT-GUANO detection outside the coded FOV
  67. GRB 220310A: MITSuME Akeno optical observation
  68. GRB 220317A: Fermi GBM Final Real-time Localization
  69. GRB 220315A: MASTER Global Robotic Net optical observations
  70. GRB 220311A: Fermi GBM observation
  71. GRB 220306B: Swift/UVOT Upper Limits
  72. GRB 220315A: Fermi GBM Final Real-time Localization
  73. GRB 220311A: MITSuME Akeno optical upper limits
  74. IPN triangulation of GRB 220310A
  75. GRB 220310C: Fermi GBM observation
  76. GRB 210722A: TAROT Reunion observatory optical light curve
  77. GRB 210222B: TAROT Reunion observatory optical light curve
  78. GRB 201021C: TAROT Reunion observatory optical light curve
  79. GRB 220310A: K-800 of Terskol observatory optical upper limit
  80. GRB 220310A: [KAO-Egypt] SDSS r, i observation
  81. GRB 220310C: Swift-XRT observations
  82. Konus-Wind detection of GRB 220310A
  83. GRB 220310C: Swift ToO observations
  84. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  85. GRB 220311A: MASTER OT retraction
  86. GRB 220311A: A long GRB detected by INTEGRAL
  87. GRB 220311A: Fermi GBM Final Real-time Localization
  88. ZTF22aabjpxh/AT2022cva (GRB 220219B): evidence of supernova in LBT spectra
  89. GRB 220310A: GIT confirmation of optical afterglow.
  90. GRB 220306B: Nanshan/NEXT optical upper limit
  91. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
  92. GRB 220310C: Fermi GBM Final Real-time Localization
  93. Fermi GBM Detection of GRB 220308A
  94. GRB 220308A: AGILE detection
  95. GRB 220310A: MASTER optical counterpart detection
  96. GRB 220310A: Swift ToO observations
  97. GRB 220310A: CALET Gamma-Ray Burst Monitor detection
  98. Fermi GRB 220310B: Global MASTER-Net observations report
  99. GRB 220310B: Fermi GBM Final Real-time Localization
  100. GRB 220308B: Fermi GBM detection

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