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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"

26507 results found.

  1. GRB 251013C: SVOM/ECLAIRs refined analysis
  2. GRB 251013D: Swift-XRT observations
  3. Swift Trigger 1404295: possible GRB 251015A
  4. GRB 251014B: Swift-XRT observations
  5. GRB 251014B: Swift/UVOT Upper Limits
  6. GRB 251014B: VLT/FORS2 Optical Observation
  7. GRB 251014D: Swift/UVOT Upper Limits
  8. GRB 251014D: Swift-XRT afterglow detection
  9. GRB 251013C: MAO/AZT-22 optical observations
  10. GRB 251011B: SVOM/VT optical upper limit
  11. GRB 251013D: Fermi GBM Observation
  12. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  13. GRB 251014A: Swift-BAT refined analysis
  14. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  15. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  16. GRB 251014D: Swift detection of a burst
  17. GRB 251014A: PRIME near-infrared upper limits
  18. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  19. GRB 251014A: VLT/FORS2 Optical Observation
  20. GRB 251012A: Glowbug gamma-ray detection of a likely short burst
  21. GRB 251013C: MarSEC, optical afterglow photometry
  22. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  23. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  24. GRB 251013C: Bassano Bresciano Observatory optical observations
  25. GRB 251013C: Early and late-time optical counterpart detection by LCO
  26. GRB 251013C: Fermi GBM Observation
  27. GRB 251014A: DDOTI Upper Limit
  28. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  29. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  30. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  31. GRB 251013C: Asiago optical observations
  32. GRB 251013C: ABObservatory optical observations
  33. GRB 251014A: SAO RAS optical upper limit
  34. GRB 251014A: Fermi GBM Observation
  35. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  36. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  37. GRB 251013C: DDOTI detection of the optical afterglow
  38. GRB 251013C: Swift-XRT counterpart detection
  39. GRB 251013C: SAO RAS optical observations
  40. GRB 251013C: LCO optical afterglow detection
  41. GRB 251013C: LAST detection of optical counterpart
  42. GRB 251013C: SVOM/VT optical observation
  43. GRB 251013C: SVOM detection of a burst
  44. GRB 251013B: SVOM/GRM observation
  45. GRB 251013A: SVOM/GRM observation
  46. GRB 251003A: Mondy optical upper limit
  47. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  48. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  49. GRB 251011B inspection: MASTER orphan GRB detection
  50. GRB 251011B: Swift/UVOT Upper Limits
  51. GRB 251011B: SVOM/GRM observation
  52. GRB 251011B: Swift-XRT refined Analysis
  53. GRB 251011B: Fermi GBM Observation
  54. GRB 251011B : MASTER optical observations
  55. GRB 251011B: Enhanced Swift-XRT position
  56. GRB 251011B: Swift detection of a burst
  57. GRB 251007B: Swift/UVOT Upper Limits
  58. GRB251007A: Swift/UVOT Detection
  59. GRB 251009B (short): Glowbug gamma-ray detection
  60. GRB 251007A: SVOM/GRM observation
  61. GRB 251007B - SVOM/ECLAIRs refined analysis
  62. SVOM/sb25101004: SVOM detection of a stellar flare
  63. GRB 251006A: Fermi GBM Observation
  64. GRB 251002A - SVOM/ECLAIRs refined analysis
  65. GRB 251003A: Fermi GBM Observation
  66. GRB 251006B: Fermi GBM Observation
  67. GRB 251007B: COLIBRÍ optical upper limit
  68. GRB 251007A: AstroSat CZTI detection
  69. GRB 251006B/EP251006a: EP-FXT afterglow detection
  70. GRB 250917B: iTelescope T-26 upper limit
  71. GRB 251007A: Swift-XRT refined Analysis
  72. GRB 251007A: Enhanced Swift-XRT position
  73. GRB 251007B: Swift-XRT refined Analysis
  74. GRB 251007B: Enhanced Swift-XRT position
  75. GRB 251007A: AKO Optical Upper Limit
  76. GRB 251007A: SVOM/C-GFT optical observations
  77. GRB 251005C: PRIME J-band upper limit
  78. GRB 251007A: Glowbug gamma-ray detection
  79. GRB 251007B: SVOM/C-GFT upper limit
  80. GRB 251007B: SVOM detection of a faint burst
  81. GRB 251007B: Swift detection of a burst
  82. GRB 251007A: Swift detection of a burst with an optical counterpart
  83. GRB 250702B/EP250702a: JWST/NIRCam Observations
  84. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  85. GRB 251005B: Glowbug gamma-ray detection
  86. GRB 251006B/EP251006a: SVOM/VT optical candidate
  87. GRB 251006B/EP251006a: EP-FXT follow-up observation
  88. GRB 251006B: SVOM/GRM observation
  89. GRB 251006B: COLIBRÍ optical upper limit
  90. GRB 251006B/EP251006a: EP-WXT detection
  91. GRB 251005C: SVOM/VT optical fading
  92. GRB 251005C: SVOM/GRM observation of a likely short GRB
  93. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  94. GRB 251006A (short): Glowbug gamma-ray detection
  95. GRB 251005C: COLIBRÍ optical observations
  96. GRB 251005C: VLT/X-shooter Imaging
  97. GRB 251003A: LAST optical observations
  98. GRB 251002A: LAST optical observations
  99. GRB 251005C: Swift/UVOT Upper Limits
  100. GRB 250902A: MSU cubesats detection

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