My table doesn't appear at the top of the page despite using \begin{table}[tp].
\begin{table}[t]
\flushleft
\caption{Spectral parameters and comparision with McClintock et al.,
2009}
\label{tab:table1}
\begin{tabular}
\hline
\textbf{S.}&\textbf{Day} &\textbf{MJD}
& \textbf{T\textsubscript{in}(Mcl)} & \textbf{T\textsubscript{in}}&
\textbf{$\gamma$} & \textbf{$\gamma$}&\textbf{Power law
norm}&\textbf{Power law norm}\\
\textbf{No.}&&&(KeV)&(KeV)&(Mcl)&&(Mcl)&\\
\hline
How do I place it at the top of the page?

tbpplacement option should be on the top of the page. SO, please provide a small but complete document (MWE: minimal Working Example) which will show your problem. Also see https://tex.stackexchange.com/questions/39017/how-to-influence-the-position-of-float-environments-like-figure-and-table-in-lat – Zarko Jun 11 '19 at 03:44tableenvironment on a page all by itself? – Mico Jun 11 '19 at 04:05tableis on a page all by itself (a case of a "floats-only page"). With most LaTeX document classes I'm familiar with, floats such asfigureandtableenvironments are by default centered vertically on floats-only pages. Please see the posting How to place a float at the top of a floats-only page? for information on how to override the default and, instead, place the float(s) at the top of a floats-only page. – Mico Jun 11 '19 at 06:51