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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

24455 results found.

  1. EP250220a: Optical upper limit with Kinder observations
  2. SVOM/sb25022102: SVOM detection of an X-ray transient
  3. Swift GRB250221.15: Global MASTER-Net OT detection
  4. Swift GRB250221.15: Global MASTER-Net observations report
  5. EP250220a: Xinglong optical upper limit
  6. GRB 250220B: Fermi GBM Final Real-time Localization
  7. GRB 250220A: Fermi GBM Final Real-time Localization
  8. EP250220a: Global MASTER-Net observations report
  9. Konus-Wind detection of GRB 250217C (short)
  10. GRB 250219A: NOT optical observations
  11. GRB 250219A: 1.6m Mephisto optical upper limits
  12. GRB 250219A: SVOM/VT optical counterpart
  13. GRB 250219A: Swift-XRT observations
  14. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  15. GRB 250219A: SVOM detection of a burst
  16. Konus-Wind detection of GRB 250215A / EP250215a
  17. GRB 250217C: Swift-XRT observations
  18. GRB 250217C: SVOM/GRM observation
  19. GRB 250217C: Fermi GBM Observation
  20. IPN triangulation of GRB 250217C (short)
  21. SVOM/sb25021804: SVOM detection of a long X-ray transient
  22. GRB 250213A: Swift-XRT observations
  23. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  24. Fermi GRB 250217C: Global MASTER-Net observations report
  25. GRB 250217C: Fermi GBM Final Real-time Localization
  26. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  27. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  28. Fermi GRB 250217A: Global MASTER-Net observations report
  29. GRB 250217B: Fermi GBM Final Real-time Localization
  30. GRB 250217A: Fermi GBM Final Real-time Localization
  31. Fermi GRB 250216A: Global MASTER-Net observations report
  32. GRB 250216A: Fermi GBM Final Real-time Localization
  33. EP250212a: FTW optical and NIR upper limits
  34. GRB 250215A: Fermi GBM Observation
  35. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  36. GRB 250215A: SVOM/GRM observation
  37. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  38. EP250215a: Global MASTER-Net observations report
  39. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  40. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  41. Fermi GRB 250215A: Global MASTER-Net observations report
  42. GRB 250215A: Fermi GBM Final Real-time Localization
  43. Fermi trigger No 761206993: Global MASTER-Net observations report
  44. GRB 250213A：SVOM/VT optical candidate
  45. EP250207b: Xinglong optical upper limit
  46. Fermi GRB 250214A: Global MASTER-Net observations report
  47. GRB 250214A: Fermi GBM Final Real-time Localization
  48. EP250212a: Xinglong optical upper limit
  49. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  50. GRB 250213A: SVOM detection of a burst
  51. EP250212a: Global MASTER-Net observations report
  52. GRB 250205A: Leavitt Observatory optical upper limit
  53. GRB 250210A: GRBAlpha detection
  54. EP250207B: Chandra localization of the X-ray counterpart
  55. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  56. EP250207b: VLA radio upper limits
  57. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  58. GRB250101A: Radio upper limits from GMRT observations
  59. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  60. Fermi GRB 250212A: Global MASTER-Net observations report
  61. Fermi trigger No 760945500: Global MASTER-Net observations report
  62. EP250207b: NOT optical counterpart candidate
  63. GRB 250211B: A long GRB detected by INTEGRAL
  64. Integral GRB250211.89: Global MASTER-Net observations report
  65. GRB 250212A: Fermi GBM Final Real-time Localization
  66. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  67. GRB 250207A: Fermi GBM Observation
  68. GRB 250206A: Fermi GBM Observation
  69. IceCube-250207A: One candidate from the Zwicky Transient Facility
  70. EP250207b: Tentative z-band brightening source
  71. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  72. Konus-Wind detection of GRB 250207A
  73. Konus-Wind detection of GRB 250206A
  74. EP250207b: Global MASTER-Net observations report
  75. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  76. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  78. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  79. EP250207b: Gemini GMOS-N z-band observations
  80. EP250207A: Upper limits from Fermi-GBM Observations
  81. EP250207b: a new X-ray transient detected by Einstein Probe
  82. Fermi GRB 250210A: Global MASTER-Net observations report
  83. GRB 250210A: Fermi GBM Final Real-time Localization
  84. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  85. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  86. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  87. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  88. IceCube Alert 250207.09: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  90. GRB 250204B: GRBAlpha detection
  91. GRB 250204A: GRBAlpha detection
  92. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  93. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  94. GRB 250207A: 1.3m DFOT Optical observations
  95. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  96. GRB 250206A: Swift-XRT observations
  97. GRB 250207A: Swift-BAT refined analysis
  98. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  99. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  100. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization

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