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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"

26537 results found.

  1. EP 251220a: COLIBRÍ detection of the optical counterpart
  2. GRB 251221A: Swift detection of a burst
  3. EP251220a: EP detection of a fast X-ray transient
  4. GRB 251219A: SVOM/GRM observation of a short burst
  5. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  6. GRB 251215A: Swift-XRT afterglow detection
  7. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  8. IceCube-251218A: COLIBRÍ optical upper limits
  9. GRB 251214B: VIRT Optical Upper Limit
  10. Fermi trigger No 787736968: Global MASTER-Net observations report
  11. GRB 251215A: Swift/UVOT Upper LImits
  12. GRB 251215A: Fermi GBM Observation
  13. GRB 251202A/EP251202a: Koshka optical upper limit
  14. GRB 251214B: Mondy optical upper limit
  15. GRB 251215A: COLIBRÍ optical upper limit
  16. EP251214b: KAIT optical upper limit
  17. GRB 251215A: Swift-XRT observations
  18. EP251214a: Optical upper limit with Kinder observations
  19. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  20. GRB 251215A: Glowbug gamma-ray detection
  21. GRB 251214B: UAFO optical upper limit
  22. GRB 251214B: VLT/X-shooter observations
  23. GRB 251202A: radio detection with the VLA
  24. EP251214b : Einstein Probe detection of a fast X-ray transient
  25. EP251214b : Einstein Probe detection of a fast X-ray transient
  26. GRB 251214B: AbAO optical observations
  27. GRB 251214B: LCO detection of the optical counterpart
  28. GRB 251214B: Fermi GBM Observation
  29. EP251214b (EP trigger 01709250023): LCO optical limits
  30. GRB 251203B: AbAO optical observations
  31. GRB 251214B: Swift-XRT refined Analysis
  32. GRB 251213A: SVOM/GRM observation
  33. EP251214a: KAIT optical upper limit
  34. GRB 251214D: AstroSat CZTI detection of a long burst
  35. GRB 251213A: AstroSat CZTI detection
  36. GRB 251214B: Swift/UVOT Detection
  37. GRB 251214B: COLIBRÍ observations of the afterglow
  38. EP251214a: EP-FXT non-detection and upper limit
  39. GRB 251214B: 1.3m DFOT optical detection
  40. GRB 251214B: Enhanced Swift-XRT position
  41. GRB 251214B: Xinglong-2.16m optical observation
  42. GRB 251214B : MASTER optical afterglow detection
  43. GRB 251214B: SVOM/C-GFT optical observations
  44. EP251214a: COLIBRÍ optical upper limit
  45. EP251214.305: COLIBRÍ optical upper limit
  46. GRB 251214B: Swift detection of a burst with an optical counterpart
  47. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  48. EP251212a: KAIT optical upper limit
  49. EP251212a / GRB 251212A: AstroSat CZTI detection
  50. EP251212a: EP-FXT follow-up observation
  51. EP251212a : COLIBRÍ optical upper limit
  52. EP251212a: Einstein Probe detection of an X-ray transient
  53. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  54. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  55. IceCube-251210A: DDOTI Optical Upper Limit
  56. GRB 251209A: Fermi GBM observation
  57. GRB 251205A: 1.3m DFOT optical upper limit
  58. GRB 251209A: AstroSat CZTI detection
  59. EP251124a: Mondy optical upper limit
  60. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  61. EP251130a: Mondy and AbAO optical observations
  62. Fermi GBM Sub-Threshold Detection of GRB 251205A
  63. GRB 251208A: Glowbug gamma-ray detection
  64. GRB 251208B: COLIBRÍ optical upper limits
  65. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  66. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. GRB 251208B: Swift-XRT afterglow detection
  68. GRB 251208D: LAST optical upper limit
  69. GRB 251208D: LCO analysis of the XRT sources
  70. GRB 251208B: Fermi GBM Observation
  71. GRB 251208B: GROWTH-India Telescope optical upper limits
  72. GRB 251205A: J-band detection with WINTER
  73. GRB 251208D: Swift-XRT observations
  74. GRB 251208A: SVOM/GRM observation of a short burst
  75. GRB 251208C: SVOM/GRM observation of a short burst
  76. GRB 251205A: Liverpool Telescope further optical follow-up observations
  77. GRB 251208D: LCO optical upper limits
  78. GRB 251208D: SVOM possible detection of a faint burst
  79. GRB 251206A: SVOM detection of a burst through offline search
  80. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  81. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  82. GRB 251205A: Liverpool Telescope further optical follow-up observations
  83. The EP-WXT trigger 01709249380 is likely a flaring star
  84. GRB 251205A: GROWTH-India Telescope optical observations
  85. GRB 251205A: Swift-XRT refined Analysis
  86. GRB 251205A: Swift/UVOT Detection
  87. GRB 251205A: Liverpool Telescope optical follow-up observations
  88. GRB 251203C: Swift/UVOT Upper Limit
  89. Konus-Wind detection of GRB 251118A
  90. GRB 251205A: COLIBRÍ optical observations
  91. GRB 251205A: NOT optical observations
  92. GRB 251205A: Enhanced Swift-XRT position
  93. Swift GRB 251205A : MASTER OT detection with host galaxy
  94. GRB 251205A: Swift detection of a burst with an optical afterglow
  95. GRB 251203C: SVOM/ECLAIRs refined analysis
  96. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  97. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  98. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 251202A: SVOM/GRM observation
  100. GRB 251203A: SVOM/GRM observation

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