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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"

2974 results found.

  1. EP260101a: Global MASTER-Net observations report
  2. GRB 260101A: Swift detection of a burst with an optical counterpart
  3. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  4. Fermi GRB 251228A: Global MASTER-Net observations report
  5. SVOM GRB251227.07: Global MASTER-Net observations report
  6. IceCube Alert 251225.84: Global MASTER-Net observations report
  7. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  8. IceCube Alert 251218.85: Global MASTER-Net observations report
  9. Fermi GRB 251217A: Global MASTER-Net observations report
  10. Fermi GRB 251215A: Global MASTER-Net observations report
  11. GRB 251214B: UAFO optical upper limit
  12. GRB 251202A: radio detection with the VLA
  13. EP251214b: Global MASTER-Net observations report
  14. GRB 251214B: LCO detection of the optical counterpart
  15. EP251214a: Global MASTER-Net observations report
  16. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 251209A: Fermi GBM observation
  18. Fermi GRB 251208C: Global MASTER-Net observations report
  19. GRB 251208B: GROWTH-India Telescope optical upper limits
  20. GRB 251208A: Fermi GBM Final Real-time Localization
  21. GRB 251205A: Liverpool Telescope further optical follow-up observations
  22. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  23. GRB 251205A: Swift detection of a burst with an optical afterglow
  24. GRB 251126B: Fermi GBM Final Localization
  25. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  26. EP251129a/GRB 251129A: NOWT Detection
  27. Swift GRB 251201B : MASTER optical counterpart detection
  28. Swift GRB 251201B: Global MASTER-Net observations report
  29. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  30. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  31. GRB 251129A: Correction to the position of the optical counterpar
  32. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  33. SVOM GRB251129A: Global MASTER-Net observations report
  34. GRB 251126A: Swift-BAT refined analysis
  35. GRB 251126A: Mondy and SAO RAS optical observations
  36. Fermi GRB 251125B: Global MASTER-Net observations report
  37. EP251118A: 3.6m DOT optical afterglow detection
  38. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  39. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  40. EP251122a: Global MASTER-Net observations report
  41. GRB 251122A / EP251122a: SVOM detection of a long burst
  42. EP251118A / GRB 251118C : MASTER optical counterpart observations
  43. EP251118a: Global MASTER-Net observations report
  44. LAT GRB251118.86: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  46. GRB 251116C: SVOM/ECLAIRs refined analysis
  47. LAT GRB251117.51: Global MASTER-Net observations report
  48. GRB 251116C: Swift/BAT arcminute localization of a burst
  49. GRB 251116C: SVOM detection of a burst
  50. GRB 251112A: Swift-BAT refined analysis
  51. Fermi GRB 251114A: Global MASTER-Net observations report
  52. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  53. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  54. GRB 251111A: SVOM/VT optical observations with X-band data
  55. GRB 251111A: SVOM/VT optical observations with VHF data
  56. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  57. Fermi trigger No 784329591: Global MASTER-Net observations report
  58. Fermi trigger No 784279167: Global MASTER-Net observations report
  59. SVOM GRB251108.54: Global MASTER-Net observations report
  60. SVOM GRB251106.83: Global MASTER-Net observations report
  61. GRB 251106A: MASTER optical observations
  62. GRB 250920C: TERI Gamma-ray detection
  63. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  64. Fermi GRB 251105A: Global MASTER-Net observations report
  65. GRB 251103A: WFST optical observations
  66. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  67. GRB 251103B: MITSuME Akeno optical upper limits
  68. Fermi GRB 251103A: Global MASTER-Net observations report
  69. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  70. GRB 251028A: MAXI/GSC detection
  71. Fermi GRB 251025C: Global MASTER-Net observations report
  72. GRB 251023A: SVOM/GRM observation
  73. EP251023b: Global MASTER-Net observations report
  74. GRB 251023A: Glowbug gamma-ray detection
  75. EP251023a: COLIBRÍ optical observations
  76. Fermi GRB 251023A: Global MASTER-Net observations report
  77. GRB 251023A: Fermi GBM Final Localization Correction
  78. EP251021b: BOOTES-7 optical upper limit
  79. GRB 250911A: MAXI/GSC detection
  80. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 251017A: COLIBRÍ optical observations of a late plateau
  82. IceCube-251018A: Global MASTER-Net observations report
  83. Fermi GRB 251016B: Global MASTER-Net observations report
  84. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  85. IceCube Alert 251014.77: Global MASTER-Net observations report
  86. GRB 251014A: Swift-BAT refined analysis
  87. GRB 251014D: Swift detection of a burst
  88. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  89. GRB 251013C: BOOTES-6 early optical detection
  90. GRB 251013A: SVOM/GRM observation
  91. GRB 250919A: TERI gamma-ray detection
  92. EP251006a: Global MASTER-Net observations report
  93. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  94. Swift GRB 251007A: Global MASTER-Net observations report
  95. GRB 251007B: SVOM detection of a faint burst
  96. GRB 250702B/EP250702a: JWST/NIRCam Observations
  97. Fermi GRB 251006B: Global MASTER-Net observations report
  98. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  99. Fermi trigger No 780609036: Global MASTER-Net observations report
  100. GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+

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