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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"

23632 results found.

  1. EP251130a: SVOM/VT optical observation
  2. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  3. Fermi GRB 251202A: Global MASTER-Net observations report
  4. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  5. GRB 251201B: Swift-XRT refined Analysis
  6. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 251202A: Fermi GBM Final Real-time Localization
  8. GRB 251201A: SVOM/GRM observation of a burst
  9. GRB 251201B: SVOM/VT optical fading
  10. Swift GRB 251201B : MASTER optical counterpart detection
  11. Swift GRB 251201B: Global MASTER-Net observations report
  12. GRB 251201B: Fermi GBM Final Real-time Localization
  13. SVOM GRB251201.19: Global MASTER-Net observations report
  14. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  15. EP251130a: KAIT optical observations
  16. EP251130A: Optical observation from 1.3m DFOT
  17. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  18. EP251130a: JinShan optical observations
  19. Fermi GRB 251130B: Global MASTER-Net observations report
  20. GRB 251127A: SVOM/GRM observation
  21. IceCube Alert 251130.75: Global MASTER-Net observations report
  22. IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
  23. GRB 251130B: Fermi GBM Final Localization Correction
  24. EP251130a: Global MASTER-Net observations report
  25. GRB 251130B: Fermi GBM Final Real-time Localization
  26. EP251129a/GRB 251129A: EP-FXT follow-up observations
  27. GRB 251130A: Fermi GBM Final Real-time Localization
  28. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  29. GRB 251128A: SVOM/GRM observation of a long burst
  30. SVOM GRB 251129A : MASTER optical counterpart detection
  31. GRB 251129A / EP251129a: SVOM/VT optical fading
  32. EP251129a: Global MASTER-Net observations report
  33. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  34. GRB 251128A: Fermi GBM Observation
  35. GRB 251129A: SVOM detection of a burst
  36. SVOM GRB251129A: Global MASTER-Net observations report
  37. GRB 251129A: SVOM detection of a burst
  38. GRB 251126A: Swift-BAT refined analysis
  39. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  40. Fermi GRB 251128A: Global MASTER-Net observations report
  41. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  42. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  43. GRB 251126A NUTTelA-TAO Early Measurements
  44. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  45. GRB 251128A: Fermi GBM Final Real-time Localization
  46. GRB251126A: Continued optical observation from 1.3m DFOT
  47. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  48. GRB 251126A: 1.3m DFOT optical afterglow detection
  49. GRB 251125B: GECAM-B detection
  50. Fermi GRB 251127A: Global MASTER-Net observations report
  51. GRB 251127A: Fermi GBM Final Real-time Localization
  52. GRB 251126A: Asiago i-band detection
  53. Swift GRB 251126A: Global MASTER-Net observations report
  54. GRB 251121A: Fermi GBM Observation
  55. GRB 251126A: Swift detection of a burst
  56. EP251124b follow-up observation by EP-FXT
  57. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  58. Fermi GRB 251125B: Global MASTER-Net observations report
  59. GRB 251125B: Fermi GBM Final Real-time Localization
  60. EP251124b: Global MASTER-Net observations report
  61. EP251124a: Xinglong GWAC-F60A optical observation
  62. Fermi GRB 251125A: Global MASTER-Net observations report
  63. GRB 251125A: Fermi GBM Final Real-time Localization
  64. EP251124a: Global MASTER-Net observations report
  65. GRB 251124A: Fermi GBM Localization by automated pipeline
  66. GRB 251122B: Fermi GBM Final Localization
  67. Fermi GRB 251124a: Global MASTER-Net observations report
  68. GRB 251124a: Fermi GBM Final Localization
  69. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  70. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  71. EP251124a: GROWTH-India Telescope optical upper limits
  72. GRB 251116C: Swift-XRT confirmation of fading
  73. GRB 251122A/EP251122a: FTW optical and NIR observations
  74. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  75. The EP-WXT trigger 01709248783 is likely a flaring star
  76. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  77. EP251118A: 3.6m DOT optical afterglow detection
  78. GRB 251122A / EP251122a: EP-FXT counterpart detection
  79. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  80. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  81. GRB 251122A / EP251122a: LCO optical upper limits
  82. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  83. EP251122a: Global MASTER-Net observations report
  84. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  85. GRB 251122A / EP251122a: SVOM detection of a long burst
  86. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  87. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  88. EP251118a: Xinglong-2.16m optical observation
  89. GRB 251115A: Fermi GBM Observation
  90. The EP-WXT trigger 01709248635 is likely a flaring star
  91. GRB 251121A: Fermi GBM Final Real-time Localization
  92. Fermi trigger No 785388351: Global MASTER-Net observations report
  93. EP251118A: 1.3m DFOT optical afterglow detection
  94. GRB 251118A: Glowbug gamma-ray detection
  95. GRB 251118A: Fermi GBM Observation
  96. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  97. GRB 251118A: GECAM-B detection
  98. EP251118a / GRB 251118C: SVOM/VT optical observation
  99. The EP-WXT trigger 01709248403 is likely a flaring star
  100. GRB 251118A: NuSTAR detection of bright prompt emission

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